心血管疾患心血管疾患とは、心臓発作、脳卒中、下肢の動脈閉塞など、心臓や血管に関する問題の総称です。. による予防 レジスタンストレーニングResistance training is working your muscles against a load — weights, bands, or your own body weight.疫学的基礎、臨床比較分析、および生体分子メカニズム

女性における筋力トレーニングと心血管の長寿に関する疫学的基礎

心血管疾患（CVD）予防の臨床的パラダイムは、歴史的に〜を優先してきた 有酸素運動有酸素運動は、早歩き、サイクリング、水泳、ジョギングのように、しばらくの間呼吸が激しくなるような持続的な運動のことです。. 処方箋¹. しかし、大規模な 前向きコホート前向きコホート研究は、健康な人々を登録し、その特徴を記録し、その後何が起こるかを待って観察する。. データにより、レジスタンストレーニングが心血管の健康、特に女性の心血管の健康における、独立した非常に強力な調節因子であることが確立されている。¹. Journal of the American College of Cardiology（JACC）誌に発表された前向きコホート分析では、米国の女性登録看護師117,025人のデータが統合された。このデータは、Nurses’ Health Study（NHS：n＝45,669、ベースライン時の平均年齢66.8歳）およびNurses’ Health Study II（NHS II：n＝71,356、ベースライン時の平均年齢48.1歳）から抽出されたものである。¹. 平均14.5年の追跡期間（総計1,630,964人年）にわたり、研究者らは主要心血管イベントの発生を追跡した。その定義は 複合エンドポイント複合のエンドポイントは、いくつかの異なる転帰を一つにまとめ、最初に発生したものをカウントします。. 非致死性または致死性の 心筋梗塞詳しい項目については心臓発作をご覧ください。. (MI), 脳卒中脳卒中は、脳の一部への血流が詰まりまたは出血によって止まるときに起こります。., 冠動脈バイパス術CABGは開心術の一つであり、外科医が体の他の部位（通常は脚の静脈や胸壁の動脈）から採取した血管を使用して、閉塞した冠状動脈を迂回して血液を流す新しい経路を作る手術です。., 、または 経皮的冠動脈形成術（PCI）経皮的冠動脈インターベンションは低侵襲の手術であり、一般にはステント留置の有無を問わず血管形成術として知られ、カテーテルを用いて閉塞した冠動脈を開通させるものです。これは、看護師健康調査（Nurses' Health Study）の分析において追跡された複合主要心血管疾患（CVD）エンドポイントの4つの構成要素の1つとして、記事に含まれています。.¹.

本調査の主な結果によると、週に2時間以上のレジスタンストレーニングを行っている女性は、レジスタンストレーニングを行っていない女性に比べ、主要な心血管疾患（CVD）の発症リスクが20%低くなっており、これは多変量調整後の ハザード比ハザード比は、2つのグループでイベントが起こる速さを比較するものです。比率が0.75の場合、治療群でのイベント発生率が4分の一減少し、対照群の4分の3であったことを意味します。. (HR) 0.80（95% 信頼区間：0.69～0.92、Pₜtrend = 0.007）¹. これらのモデルが調整されたとき、 ボディ質量指数ボディ・マス・インデックス（BMI）とは、身長と体重から計算される数値であり、体格の大まかな目安として使用されます。. (BMI) と、2型などの代謝性疾患 糖尿病糖尿病は、体が十分なインスリンを作らないか、あるいは作られたインスリンに反応しなくなることで、血糖値が常に高すぎる状態になる疾患です。., 高血圧Hypertension is the medical term for high blood pressure., 高コレステロール血症Hypercholesterolemia is an abnormally elevated level of cholesterol-carrying particles in the blood, typically caused in primate experiments by feeding a diet high in dietary cholesterol and saturated fat, and associated with accelerated plaque formation in artery walls., 、およびそれぞれの薬物療法について、その関連性は統計的に有意であり、ハザード比（HR）は0.86（95％信頼区間：0.75～0.98）であった。¹. これは、筋力トレーニングに関連する心臓保護効果が、肥満度や代謝性疾患の違いだけでは十分に説明できない可能性が高いことを示している。しかし、観察研究における関連性であるため、それ単体では独立した因果メカニズムを証明することはできず、残余 交絡Confounding is when a hidden third factor makes two unrelated things look connected. 可能のままである¹.

臨床コホートパラメータ	看護師健康調査（NHS）	看護師健康調査第2弾（NHS II）	プールコホート解析
コホートサイズ (n)	45,669人の女性1	71,356人の女性1	117,025人の女性1
ベースライン時の平均年齢	66.8年1	48.1年1	—
追跡期間	18年間（2002–2020年）1	14年間（2003年～2017年）1	14.5年（平均）1
延べ人年	—	—	1,630,964人年1
重大な心血管イベントの発生	—	—	5,459件1
一次ばく露評価	4年ごとの腕と脚の抵抗運動時間1	4年ごとの腕と脚の抵抗運動時間1	時間変動型累積平均1
心血管疾患のハザード比（週2時間以上 vs. なし）	—	—	HR = 0.80（95％信頼区間：0.69～0.92）1
MIハザード比（週2時間以上 vs. なし）	—	—	HR = 0.56（95％信頼区間：0.41～0.76）1
脳卒中のハザード比（週2時間以上対なし）	—	—	HR = 0.99（95％信頼区間：0.80–1.23）1

表1. 統合コホートの特徴および主要心血管エンドポイント（JACC／ナース・ヘルス・スタディーズ）。.

重要なことに、特定の心血管エンドポイントを検討すると、明確な差異が見られる。 レジスタンストレーニングの保護的関連性は心筋梗塞において特に顕著であり、週2時間以上の実施はリスクの44%低下と関連している（HR = 0.56、95% CI: 0.41–0.76）。¹. 。一方、脳卒中のリスクについては、統計的に有意な関連は認められなかった（HR = 0.99、95％信頼区間：0.80–1.23）。¹. この臨床的な分岐は、筋力トレーニングがもたらす代謝的、脂質異常症的、および全身的な影響が、冠動脈に対してより大きな影響を及ぼすという事実と整合しており、 脳血管疾患Disease affecting the blood vessels supplying the brain, including stroke; cited alongside cardiovascular disease as an outcome reduced by vegetarian and vegan diets in an umbrella review of meta-analyses., しかし、ヌルストロークの発見は、限定的な 統計的検出力Statistical power is a study's ability to detect a real effect if one exists. It depends mostly on how many events occur. 脳卒中特異的解析、競合する脳卒中サブタイプ（心原性および出血性メカニズムを含む）、または残余交絡因子については、根本的な説明はいまだ不確実である¹.

さらに、身体活動への曝露の時間的特性からは、一貫した傾向が認められる。主要な心血管疾患（CVD）のリスク低下が認められたのは、筋力トレーニングの累積平均時間が週1時間以上であり、かつ追跡期間の75%以上にわたりこの習慣を一貫して維持していた女性のみに限られていた。¹. 。一貫性が中程度または低い（評価サイクルのうち75%未満でトレーニング閾値を満たした）女性では、このコホートにおいて心血管イベントの統計的に有意な減少は認められなかった。¹. 心筋梗塞のリスクが著しく低下したのは、複数の心血管系の改善によるものと考えられる 危険因子危険因子とは、高コレステロール粒子、高血圧、喫煙、糖尿病、家族歴など、病気にかかる可能性を高めるものです。.—を含めて 血圧血圧とは、血液が動脈の壁を押す力ののことです。120/80のように2つの数字で表されます。上の数字は心臓が収縮するときの圧力で、下の数字は弛緩するときの圧力です。., インスリン感受性インスリン感受性とは、細胞がインスリンに対してどれだけよく反応するかということです。それはインスリン抵抗性の反対です。., 体組成, 炎症炎症は、怪我や侵入物とみなしたものに対する免疫システムの反応です。これにより腫れや熱、そして浄化細胞がもたらされます。., 血管内皮機能血管の内側を覆う内膜が血管の緊張、炎症、血液凝固を調節する能力。健康な内視細胞は一酸化窒素を放出し、動脈をリラックスさせ、プラーク形成に対する抵抗力を保ちます。., 、および脂質代謝——冠動脈に対する直接的な影響が実証されたことによるものではなく、 歯垢プラークとは、動脈の壁の内側にコレステロール、免疫細胞、瘢痕組織、カルシウムが蓄積したものです。. 生物学、これは 観察研究観察研究は、人々がすでにしていることを観察し、その人に何が起こるかを追跡するものです。誰も何も割り当てられません。. 測定しなかった¹.

トレーニング量に関しては、筋力トレーニングの週あたりの実施時間が1時間増えるごとに、主要な心血管疾患（CVD）のリスクが5%低下することが示されました（HR = 0.95、 95% 信頼区間：0.92–0.99）のリスク低下、および心筋梗塞のリスクが14%低下すること（HR = 0.86、95% 信頼区間：0.76–0.97）と関連していた。¹. 解剖学的分析の結果、上半身（腕）と下半身（脚）の両方の筋肉群を取り入れたプログラムは、特定の四肢のみを対象とした単独のトレーニングプロトコルと比較して、心血管疾患のリスクとの間に有意に強い逆相関を示すことが明らかになった。¹.

統合された動作パターンと身体活動モダリティの相乗効果

現代の疫学的サーベイランスから得られる重要な知見の一つは、心血管疾患のリスク評価は、個々の運動行動を単独で捉えるのではなく、総合的な運動パターンの観点から行う必要があるということである。¹. JACC コホート研究A cohort study follows a large group of people over time, recording what they eat or do and what happens to their health years later. 筋力トレーニング、有酸素運動、および座りがちな行動（余暇時の座り時間を表す検証済みの指標としてテレビ視聴時間で表される）の複合的な影響を調査した¹. 主要なCVDのリスクが最も低かったのは、有酸素運動を週に15メッツ・時（MET-hours）以上（中高強度の運動に換算して週約150分にほぼ匹敵）、週に1時間以上の定期的なレジスタンス訓練の実施、および座位でのテレビ視聴を1日2時間未満に制限するという3つの行動推奨事項を同時に満たした女性グループであった。¹. 。この最適なサブグループでは、推奨事項をいずれも満たしていない、活動量が少なく座りがちな同世代と比較して、主要な心血管疾患（CVD）のリスクが40%減少した（HR = 0.60、95% CI：0.53–0.69）。¹.

対照的に、有酸素運動と低座り時間という両方の目標を達成したものの、筋力トレーニングを全く行わなかった女性では、リスクの低下幅は27%にとどまり、その効果はそれほど顕著ではなかった（HR = 0.73、95% CI：0.67–0.80）。¹. この傾向は、有酸素運動単独の効果を超えた、レジスタンストレーニングによる追加的な心血管のベネフィットと一致している。¹. 。一方、有酸素運動のガイドラインを満たしていない場合でも、筋力トレーニングと座っている時間の短縮を組み合わせることで予防効果が維持され、主要な心血管疾患（CVD）のリスクを31%（HR = 0.69、 95% CI: 0.56–0.85）、心筋梗塞のリスクを44%（HR = 0.56、95% CI: 0.38–0.85）低減した。¹.

行動的 遵守服薬遵守とは、処方されたとおりに日々、実際に薬を服用することを意味します。. 部分群	有酸素運動の目標（15 MET-h/週以上）	有酸素運動の目標（週1時間以上）	Sedentary TV Target (<2 h/d)	Major CVD HR (95% CI)	MI HR (95% CI)
Sedentary / Inactive (Referent)	いいえ	いいえ	いいえ	1.00	1.001
Aerobic + Low TV (No Strength)	はい	いいえ	はい	HR = 0.73 (0.67–0.80)	—1
Strength + Low TV (No Aerobic)	いいえ	はい	はい	HR = 0.69 (0.56–0.85)	HR = 0.56 (0.38–0.85)1
Fully Compliant (All 3 Targets)	はい	はい	はい	HR = 0.60 (0.53–0.69)	Greatest observed reduction1

Table 2. Joint behavioral adherence subgroups and cardiovascular hazard ratios.

The physiological synergy between these modalities is further illustrated by the joint analysis of resistance training and aerobic volume¹. Women who achieved ≥2 hours/week of resistance training combined with ≥150 minutes/week of aerobic activity demonstrated a 45% lower risk of myocardial infarction compared to completely inactive individuals, establishing that resistance work acts additively to, rather than as a substitute for, traditional cardiovascular conditioning¹.

Long-Term Mortality Dynamics and Dose-Response Thresholds

To evaluate the impact of resistance training on all-cause and cause-specific mortality over extended follow-up, researchers have analyzed long-term behavioral data spanning three decades². A comprehensive cohort evaluation published in the British Journal of Sports Medicine (BJSM) analyzed a sample of 147,374 participants, consisting of 31,540 men and 115,834 women from the Health Professionals Follow-up Study (HPFS, followed from 1992 to 2022), the Nurses’ Health Study (NHS, followed from 2002 to 2021), and the Nurses’ Health Study II (NHS II, followed from 2003 to 2021)². Over up to 30 years of follow-up, during which 35,798 deaths were recorded, investigators observed a highly nuanced, non-linear 用量反応関係A dose-response relationship describes how the magnitude of a biological effect changes as the amount of an exposure (such as weekly exercise minutes) increases; in this article, resistance training shows a non-linear dose-response for mortality, with benefits plateauing around 120 minutes per week and a J-shaped curve emerging at very high volumes in older women.².

The data demonstrates that a moderate volume of resistance training, specifically between 90 and 120 minutes per week, represents the optimal operational range for maximizing survival benefits². This range was associated with a 13% lower risk of 全因死亡率全死因死亡とは、心疾患に限らず、あらゆる原因による死亡を意味し、研究が測定できる最も広範で、ごまかしが最も効かない結果です。. (HR = 0.87, 95% CI: 0.81–0.95), a 19% lower risk of cardiovascular disease mortality (HR = 0.81, 95% CI: 0.67–0.97), and a 27% lower risk of dying from neurological diseases, primarily driven by neurodegenerative conditions such as Alzheimer’s disease (HR = 0.73, 95% CI: 0.58–0.92)².

A critical finding of the 用量反応A dose-response relationship means more of something produces more of an effect, in a consistent gradient. curve is the plateau effect observed at ≥120 minutes/week². Beyond approximately 120 minutes/week, no statistically significant additional reduction in all-cause, cardiovascular, or neurological mortality was observed—an absence of further measurable benefit rather than proof that none exists². Several explanations are possible for this apparent plateau, including biological saturation of the adaptive response, exposure misclassification, regression dilution, and residual confounding; the study was observational and did not test mechanism¹.

In contrast, cancer mortality exhibits a unique quadratic relationship where protective associations are restricted exclusively to minimal training volumes². Specifically, 1 to 29 minutes/week of resistance training was associated with a 9% lower risk of cancer death (HR = 0.91, 95% CI: 0.86–0.97), and 30 to 59 minutes/week was associated with a 12% lower risk (HR = 0.88, 95% CI: 0.81–0.97)². Higher weekly durations showed no protective association against cancer mortality². The mechanisms underlying this low-dose pattern were not evaluated within the cohort and remain hypothetical; one proposed explanation is that brief bouts of acute muscular stress may enhance immune surveillance and natural killer cell activity, whereas higher volumes could promote chronic inflammatory or oxidative states, but these mechanisms are drawn from separate experimental work rather than demonstrated in this study³.

To further analyze sex-specific variations within this population, data from the BJSM study’s supplementary analyses can be compared directly². Under the multivariable-adjusted model that accounted for total aerobic physical activity, the mortality risk profiles for men and women across varying levels of weekly resistance training show subtle divergences, as detailed below²:

Resistance Training Volume	Male All-Cause Mortality HR (95% CI)	Female All-Cause Mortality HR (95% CI)	Male CVD Mortality HR (95% CI)	Female CVD Mortality HR (95% CI)
0 min/week (Referent)	1.00	1.00	1.00	1.002
1 to <30 min/week	0.95 (0.92–0.99)	0.94 (0.91–0.98)	1.00 (0.93–1.07)	0.99 (0.91–1.09)2
30 to <60 min/week	0.92 (0.86–0.97)	0.90 (0.85–0.96)	0.98 (0.88–1.09)	0.90 (0.78–1.05)2
60 to <120 min/week	0.92 (0.86–0.98)	0.89 (0.83–0.95)	0.89 (0.78–1.02)	0.93 (0.79–1.09)2
≥120 min/week	0.91 (0.82–1.01)	0.95 (0.87–1.03)	0.87 (0.71–1.07)	0.90 (0.73–1.11)2

Table 3. Sex-specific dose-response hazard ratios for all-cause and CVD mortality (BJSM supplementary analysis).

Clinical Discrepancies and the J-Shaped Mortality Hazard in Older Women

While the JACC and BJSM cohorts highlight the clinical benefits of moderate resistance training, a vital piece of epidemiological contrast is found in the Women’s Health Study (WHS) published by the American Heart Association⁴. This prospective cohort evaluated 28,879 initially healthy older women (average baseline age of 62.2 years) over an average of 12.0 years, documenting 3,055 deaths (411 from CVD and 748 from cancer)⁴. After robust adjustment for baseline demographics, 喫煙喫煙は血管の内壁を傷つけ、血圧を上げ、血液を凝固しやすくし、プラークの成長を早めます。., diet, and aerobic exercise, the investigators identified a statistically significant, non-linear J-shaped association between strength training and all-cause mortality (Pₜquadratic < 0.001, Pₜspline = 0.020)⁴.

According to the WHS spline models, the hazard ratios for mortality were significantly below 1.00 for weekly strength training durations between 1 and 145 minutes compared to no training⁴. However, for women performing ≥146 minutes/week of strength training, the hazard ratio crossed the threshold of 1.00, indicating that excessive volumes were associated with similar or potentially higher risks of all-cause and cardiovascular mortality compared to performing no strength training at all⁴. これ。 J字型曲線A statistical pattern in epidemiological data where light-to-moderate consumers of alcohol appear to have lower cardiovascular risk than both abstainers and heavy drinkers, producing a curve shaped like the letter J when risk is plotted against consumption level; the validity of this pattern has been increasingly challenged by Mendelian randomization studies and better adjustment for confounding. was also highly significant for cardiovascular disease death (Pₜquadratic = 0.007), but was absent for cancer death (Pₜquadratic = 0.41)⁴.

One possible explanation is that excessive resistance training volume may interact unfavorably with age-related cardiovascular physiology⁴. In postmenopausal and elderly women, central arteries undergo progressive structural remodeling characterized by エラスチンElastin is a structural protein in the arterial wall that allows blood vessels to stretch and recoil with each heartbeat; with age it degrades and is replaced by stiffer collagen, contributing to arterial stiffening and rising systolic blood pressure. fragmentation and collagen accumulation⁵. It is biologically plausible that when such stiffened vessels are repeatedly subjected to the high-pressure hemodynamic surges of high-volume or high-intensity resistance training, the acute vascular wall stress could contribute to arterial damage, increased left ventricular afterload, or subclinical myocardial fibrosis and arrhythmias⁵. This mechanism was not tested in the Women’s Health Study, however, and alternative explanations for the upturn in risk—including 逆因果関係Reverse causation is when the arrow points the other way — the illness caused the exposure rather than the exposure causing the illness., residual confounding, differences in underlying health status, and measurement error—remain equally plausible. Taken together, the data support a cautious interpretation: a moderate threshold (≈60 to 120 minutes/week) appears to be the range most consistently associated with lower mortality in older women, and there is no clear evidence that substantially higher volumes confer additional benefit⁴.

Direct Comparative and Synergistic Clinical Trials

To directly assess whether resistance training can match or enhance the cardiorespiratory and metabolic effects of aerobic exercise, ランダム化比較試験ランダム化比較試験では、人々を完全な偶然によって治療群または比較群に割り付け、その後両群を追跡調査します。. have examined modifications in composite cardiovascular risk profiles⁶. The Comparison of the Cardiovascular Benefits of Resistance, Aerobic, and Combined Exercise (CardioRACE) trial randomized 406 inactive, non-smoking adults aged 35–70 years with overweight or 肥満肥満とは、健康に影響を及ぼすほど過剰な体脂肪を蓄えている状態を意味します。. (BMI of 25–40 kg/m²) and elevated blood pressure into four parallel, time-matched groups: a resistance exercise group (n = 102), an aerobic exercise group (n = 101), a combined resistance plus aerobic exercise group (n = 101), or a non-exercising control group (n = 102)⁷. The active exercise cohorts performed supervised training for approximately 1 hour three times per week for 1 year, with the combined group executing 25 minutes of resistance and 25 minutes of aerobic exercise per session⁷.

The primary endpoint was a composite cardiovascular risk-factor score—comprising 収縮期血圧Systolic blood pressure is the top number — the pressure in your arteries while your heart is squeezing., LDLコレステロールLDLコレステロール（LDL-C）は、LDL粒子内に存在するコレステロールの量です。これは、ほとんどすべての標準的な検査報告書に記載されている数値です。., 、断食 グルコースブドウ糖は、細胞にエネルギーを供給するために血液が運ぶ糖です。., and percent body fat—rather than clinical cardiovascular events; the trial measured change in this composite Z-score from baseline to 1 year⁷. Compared to the control group, the composite Z-score decreased significantly in the aerobic group (ΔZ = −0.15, 95% CI: −0.27 to −0.04, P = 0.01) and the combined group (ΔZ = −0.16, 95% CI: −0.27 to −0.04, P = 0.01), but did not decrease significantly in the resistance-only group (ΔZ = −0.02, 95% CI: −0.14 to 0.09, P = 0.69)⁷. These findings suggest that for individuals with elevated blood pressure and excess body weight, resistance training alone is less effective than aerobic-containing regimens at improving a broad, multi-factor risk profile⁷.

However, examining individual risk factors reveals modality-specific strengths⁷. Percent body fat decreased significantly and uniformly by ~1.0% across all three exercise groups compared to the control (P ≤ 0.001), indicating that resistance training is effective at modifying body composition⁷. Cardiorespiratory fitnessCardiorespiratory fitness is how well your heart, lungs, and muscles work together to use oxygen during hard exercise. It is often measured as VO2 max. (VO₂peak) improved in all active groups, but the increase was significantly greater in the aerobic (+3.5 mL/kg/min) and combined (+2.7 mL/kg/min) groups compared to the resistance-only group (+1.3 mL/kg/min)⁷. Conversely, muscle strength (1RM chest and leg press) and lean body mass increased significantly only in the resistance-only group (+1.2 kg, P < 0.001) and the combined group, with the resistance-only group demonstrating the largest gains⁷. These results indicate that combined training provides a more balanced adaptation profile, capturing the cardiorespiratory benefits of aerobic work alongside the musculoskeletal and strength adaptations of resistance training within the same total exercise time².

These findings align with the broader body of comparative clinical evidence⁶. A randomized controlled trial in adults at elevated cardiovascular risk found that combined aerobic-plus-resistance training reduced both peripheral and central diastolic blood pressureDiastolic blood pressure is the bottom number in a blood pressure reading. It is the pressure in your arteries while the heart is relaxing between beats. and increased upper- and lower-body strength, whereas neither aerobic nor resistance training alone produced a statistically significant reduction in resting blood pressure⁶. システマティックレビューシステマティックレビューは、事前に宣言された方法を用いてある問いに関するすべての研究を検索し、一貫した基準によってそれらを評価する。. and meta-analyses similarly report that combined training tends to yield greater improvements across multiple risk factors—resting blood pressure, body composition, and muscular strength—than either modality performed in isolation, consistent with the additive adaptation profile observed in CardioRACE⁸.

Furthermore, resistance training plays a vital role in weight management and body composition preservation⁹. American Heart Association scientific statements note that 体重減少Weight loss means reducing body fat, whether through food changes, exercise, medication, or surgery. achieved through calorie restriction alone often leads to a concurrent loss of skeletal muscle mass⁹. Adding resistance training to caloric restriction helps preserve critical lean muscle mass, especially in middle-aged and older adults⁹. Preserving muscle is not merely a matter of physical strength; it is essential for maintaining mobility, metabolic rate, and blood glucose control⁹. Such statements also note that exercise alone, without concurrent dietary change, rarely produces clinically significant weight loss unless activity volumes are high, whereas consistently higher activity levels support long-term weight-loss maintenance; resistance training contributes by helping sustain 除脂肪体重The portion of body weight attributable to muscle, bone, and organs rather than fat; higher lean mass is associated with better metabolic health and is identified in the article as an upstream genetic driver of both VO₂ max and longevity. and metabolic rate during periods of weight change⁹.

Vascular Hemodynamics and the Mechanics of Arterial Stiffness

動脈硬化Arterial stiffness is a measure of how much an artery's wall resists expansion with each pulse of blood; it increases with age as elastin is lost and collagen accumulates, and manifests clinically as a rising systolic blood pressure alongside a falling or stable diastolic blood pressure after about age 60., a major predictor of cardiovascular morbidity and mortality, refers to the progressive loss of elasticity in large conduit arteries, which is a key feature of 血管老化The progressive structural and functional deterioration of arteries over time, characterized by loss of elasticity, increased stiffness, and accumulation of microscopic damage that makes arterial walls more susceptible to lipid deposition and chronic inflammation.⁵. At the structural level, this stiffening is characterized by the degradation and fragmentation of elastin 繊維食物繊維は、体内で消化できない植物性食品の部分です。豆類、オーツ麦、野菜、果物、全粒穀物に含まれています。., the compensatory accumulation of stiffer collagen fibers, chronic vascular wall inflammation, and microvascular 石灰化石灰化とは、カルシウムがプラークに沈着し、その一部が硬く骨状になることです。.⁵. These changes vary across different regions of the arterial network, which are categorized into central arterial stiffness (typically assessed using carotid-femoral 脈波伝播速度Pulse wave velocity measures how fast the pressure wave from each heartbeat travels along your arteries. Stiffer arteries carry it faster., cfPWV), peripheral arterial stiffness (assessed via foot-to-brachial pulse wave velocity, faPWV), and systemic arterial stiffness (evaluated using comprehensive indices like the cardio-ankle vascular index, CAVI)⁵.

Arterial Stiffness Domain	Anatomical Focus	Gold-Standard Metric	Primary Pathophysiological Drivers	Exercise Modality Response
Central Stiffness	Large elastic arteries (大動脈The aorta is the biggest artery in your body. It carries blood out of the heart and down through the chest and belly, sending branches everywhere., Carotids)	cfPWV (Carotid-femoral Pulse Wave Velocity)10	Elastin degradation, collagen cross-linkingA biochemical process in which collagen fibers within arterial walls form stable chemical bonds between adjacent molecules, reducing tissue elasticity and contributing to irreversible arterial stiffening; it is accelerated by sedentary behavior and advancing age., chronic inflammation10	Responds to long-term aerobic and moderate RT; transiently increased by high-intensity RT5
Peripheral Stiffness	Muscular conduit arteries (Femoral, Brachial)	faPWV (Foot-to-brachial Pulse Wave Velocity)10	Sympathetic nervous system overactivation, hyperinsulinemia10	Highly responsive to short-term metabolic shifts, stretching, and low-intensity RT5
Systemic Stiffness	Entire arterial tree	CAVI (Cardio-ankle Vascular Index)10	Endothelial dysfunction血管内皮機能障害とは、その薄い内側の裏打ちが十分に機能しなくなる状態です。血管が適切に拡張せず、バリア機能がより漏れやすくなります。., impaired smooth muscle relaxation, aging5	Responds to combined aerobic-resistance training and low-intensity squats5

Table 4. Regional domains of arterial stiffness and their exercise-modality responses.

歴史的に見て、, 臨床試験臨床試験とは、研究者が一方のグループに治療法を施し、もう一方のグループにはプラセボ（偽薬）または標準治療を施して、その結果を比較する研究のことです。. evaluating the impact of resistance training on vascular health have reported conflicting results⁵. Some studies suggested that chronic resistance training could impair vascular compliance, showing that intense resistance training (≥80% 1RM) can cause transient, acute increases in central arterial stiffness in young and middle-aged men⁵. This acute vascular stiffening is driven by severe intra-thoracic pressure spikes (often exacerbated by the バルサルバ法The Valsalva maneuver is a forced exhalation against a closed glottis that occurs during heavy lifting; it sharply raises intrathoracic pressure during the strain phase, but the abrupt release afterward generates violent backward pressure waves in the aorta that can trigger intimal tears in a vulnerable vessel wall.), transient elevations in systemic blood pressure, and heightened sympathetic nervous system activity during heavy lifts⁵.

However, systematic reviews and meta-regressions have demonstrated that training intensity is the primary variable governing vascular responses¹¹. Low-to-moderate-intensity resistance training effectively improves arterial compliance and endothelial function⁵. Meta-regression analysis revealed a significant correlation (P = 0.042) between resistance training intensity and changes in pulse wave velocity¹¹. Specifically, low-to-moderate-intensity resistance training significantly decreased pulse wave velocity in both young (SMD = −0.41, P = 0.03) and middle-aged adults (SMD = −0.32, P = 0.0007), whereas high-intensity resistance training did not produce a statistically significant overall reduction in arterial stiffness in either age group¹¹. For example, low-intensity resistance training with a short inter-set rest period (LSR) was shown to reduce systemic arterial stiffness and improve flow-mediated dilation (FMD)血流依存性血管拡張反応（FMD）は、血流増加に対する導管動脈（通常は上腕動脈）の拡張の程度を非侵襲的な超音波検査で測定したものであり、内皮由来の一酸化窒素シグナル伝達および血管内皮機能のマーカーとして機能する。.⁵.

Furthermore, research has identified a critical vascular interaction based on exercise order⁵. Performing aerobic exercise after resistance training has been reported to attenuate the transient increase in central 頸動脈The carotid arteries run up either side of your neck and supply blood to your brain. stiffness that follows resistance exercise, with the degree of effect varying across studies⁵. In contrast, performing aerobic exercise before resistance training does not prevent central carotid stiffening⁵. This exercise-order effect suggests that the sustained, moderate shear-stress-mediated 一酸化窒素一酸化窒素は、血管の内壁が血管に弛緩して広がるよう伝えるために産生するガスです。. release during subsequent aerobic work helps dilate and relax central vessels, counteracting the acute muscular pressure spikes of preceding resistance training⁵.

Similarly, the order of resistance training intensities can influence vascular responses¹². Performing low-intensity resistance training before high-intensity resistance training was shown to increase arterial stiffness¹². Conversely, performing high-intensity resistance training before low-intensity resistance training resulted in no change in arterial stiffness¹². This suggests that completing low-intensity exercise after heavy lifts can help mitigate central stiffening, whereas reversing this order negates the potential vascular benefits of the low-intensity component¹².

Vascular responses are also influenced by anatomical regionality and baseline health status¹³. Resistance training of the upper limbs has been shown to increase central arterial stiffness, whereas lower-limb resistance training does not alter central compliance¹². A proposed explanation is that the smaller vascular bed of the upper body may generate higher relative peripheral resistance and greater arterial wave reflection toward the aorta during contraction, although the precise physiological explanation remains uncertain¹³. Additionally, prehypertensive and hypertensive patients often demonstrate a more pronounced increase in central arterial stiffness following resistance training compared to normotensive individuals, reflecting compromised adaptive vascular compliance and heightened baseline sympathetic tone in hypertensive states¹².

Biomolecular Signaling: Myokine Transduction and Epigenetic Plasticity

At the cellular and molecular levels, the systemic effects of resistance training involve genetic, epigenetic, and endocrinological signaling pathways¹⁴. Experimental studies suggest that chronic resistance training may influence gene expression in cardiac and vascular tissues through altered DNA methylation, histone modification, and non-coding RNA expression, in ways that could promote favorable cardiovascular remodeling and reduced vascular inflammation—though the clinical significance of these findings in humans remains under investigation¹⁴.

Concurrently, contracting skeletal muscle acts as an active endocrine organ, synthesizing and secreting signaling peptides termed マイオカインMyokines are small signaling proteins secreted by skeletal muscle cells during contraction that travel through the bloodstream to exert effects on distant organs including the heart, liver, and fat tissue. Examples discussed in the article include irisin, FGF21, and decorin, which influence fat metabolism, glucose handling, and inflammation. directly into circulation¹⁵. Key myokines linked to metabolic and cardiovascular health include Interleukin-6 (IL-6)プラークの炎症時にIL-1βへの反応として産生され、肝臓へと移動してCRP産生を刺激するシグナル伝達タンパク質。したがって、血中IL-6の上昇は活動性の血管炎症を反映する。., irisinIrisin is a myokine released from skeletal muscle during exercise that promotes the conversion of energy-storing white adipose tissue into metabolically active brown adipose tissue, thereby increasing energy expenditure. The article cites it as one of the key chemical messengers linking resistance training to systemic metabolic improvements., fibroblast growth factor 21 (FGF21), myostatin, follistatin, and decorin¹⁵. Much of the mechanistic detail below is derived from animal models, cell-culture systems, and short-term human physiological studies rather than cardiovascular outcome trials, and should be read as biologically plausible signaling rather than established clinical mechanism.

[ Skeletal Muscle Contraction ]   (mechanisms largely from animal / cell / short-term studies)

|

|-> Epigenetic Adaptations (DNA Methylation, Histone Modifications, non-coding RNAs)

|     |-> Potential Cardiovascular Adaptations

|

|-> Myokine Secretion:

|     |-> IL-6Interleukin-6, or IL-6, is a signaling molecule the immune system uses to spread an inflammatory message through the body. (Rapid peak) ——> Anti-inflammatory & metabolic signaling

|     |-> Irisin —————-> Potential white adipose tissue browning

|     |-> FGF21 (RT > HIIT) ——> May influence インスリンInsulin is a hormone made by your pancreas. Its main job is letting sugar move out of your blood and into your cells for fuel. sensitivity & glucose uptake

|     |-> Decorin —————> Experimental interaction with resistin pathways

|

|-> Follistatin (FST) Activation

|-> May inhibit Myostatin (TGF-beta family)

|-> Possible reduced preadipocyte proliferation –> Potential lower visceral adiposity

These myokines exhibit distinct kinetic patterns depending on the exercise modality¹⁵. Acute resistance training, for instance, induces a significantly greater area under the curve (AUC) concentration for FGF21 compared to 高強度インターバルトレーニングHigh-intensity interval training is a structured exercise method that alternates short bouts of near-maximal effort (typically 85–95% of peak heart rate) with periods of active recovery or rest. In the cardiovascular context, HIIT protocols have been studied as a non-pharmacological intervention to reduce plaque burden and improve heart function.¹⁶. FGF21 is thought to contribute to glucose regulation and lipid utilization and may support insulin sensitivity and AMP-activated タンパク質タンパク質は、体内の筋肉や組織の構築と修復に使用される栄養素です。. kinase (AMPK) activation in muscle tissue, though most of this evidence derives from animal models, cell culture, or short-term physiological studies¹⁵. In obesity and type 2 diabetes, individuals often exhibit “FGF21 resistance,” characterized by high baseline circulating levels but impaired receptor signaling¹⁵. Chronic exercise helps restore tissue sensitivity, lowering compensatory resting FGF21 levels over time while facilitating transient, acute post-exercise spikes that support immediate metabolic homeostasis¹⁵.

Conversely, HIIT has been shown to induce a significantly greater AUC for follistatin compared to resistance training¹⁶. Follistatin (FST) and follistatin-like proteins act as inhibitors of myostatin, a member of the transforming growth factor-beta (TGF-β) family that negatively regulates muscle hypertrophy¹⁷. Because myostatin is expressed in both skeletal muscle and adipose tissue, experimental studies suggest that its inhibition by follistatin may limit preadipocyte differentiation and proliferation¹⁷. Such a reduction in fat-cell development could in turn help limit visceral adiposity—a major contributor to systemic inflammation, sympathetic overactivation, and renin-angiotensin-aldosterone system (RAAS) dysfunction—though this pathway is largely derived from experimental models rather than human outcome data¹⁵.

The contraction-induced myokine decorin also plays a key role in 代謝の健康Metabolic health describes how well your body handles blood sugar, blood pressure, fats, and body fat storage.¹⁷. Experimental evidence indicates that decorin is released from the 細胞外マトリックスThe extracellular matrix is the scaffolding of collagen and other fibers that holds tissue together and gives an artery wall its strength. during skeletal muscle contraction¹⁷. In laboratory and translational models it appears to interact with resistin at adipocyte precursors, which may modulate adipocyte metabolism and reduce pro-inflammatory signaling associated with obesity¹⁷. These studies also suggest that decorin can upregulate follistatin and suppress TGF-β1, a pro-inflammatory cytokine that correlates positively with adiposity and is elevated in overweight and obese individuals; these pathways are largely derived from experimental systems rather than human cardiovascular outcome data¹⁷.

To assess how these biomolecular pathways respond to different training intensities, a clinical trial evaluated obese males undergoing a 12-week supervised program of interval resistance training (IRT, 70 minutes/session, 3 days/week)¹⁷. Participants were randomized to low-intensity (LIIRT), medium-intensity (MIIRT), or high-intensity (HIIRT) interval resistance training¹⁷. The results demonstrated that all three intensities produced beneficial increases in decorin and follistatin, along with significant decreases in myostatin and TGF-β1¹⁷. These molecular shifts correlated with favorable improvements in clinical 脂質プロファイル総コレステロール、LDLコレステロール、HDLコレステロール、中性脂肪を測定する血液検査のパネルで、心血管リスクの評価や食事療法・薬物治療の効果のモニタリングに使用される。., including decreases in 総コレステロール総コレステロールは、悪玉も善玉も含め、すべての粒子に含まれるコレステロールの合計です。., 中性脂肪トリグリセリド（中性脂肪）は、血液中および体内の蓄積脂肪の主要な形態です。., 、および LDLLDL（低密度リポ蛋白）は、コレステロールを血液中に運ぶ主要な粒子であり、動脈壁に詰まる主原因となるものです。., and increases in HDLHDL、すなわち高密度リポタンパク質は、しばしば「善玉コレステロール」と呼ばれる粒子です。組織からコレステロールを回収し、肝臓へ運び戻します。.¹⁷. However, the changes in these myokines and in systemic cardiometabolic risk factors were more pronounced in the MIIRT and HIIRT groups than in the LIIRT group, suggesting that moderate-to-high-intensity resistance training may drive more favorable cellular and lipid adaptations¹⁷. These findings should be interpreted cautiously: the intervention was short (12 weeks) with a small sample, and the outcomes were surrogate バイオマーカーバイオマーカーとは、健康や病気の状態について教えてくれる、体内で測定可能なもののことであり、例えば、検査値、スキャン画像の結果、血圧の数値などが挙げられます。. rather than cardiovascular events¹⁷.

These acute clinical trials also highlight the physiological stress of a resistance workout³. A single strength training session causes marked acute disruptions in homeostasis, including significant elevations in 心拍数心拍数とは、心臓が1分間に鼓動する回数のことです。., blood lactate concentration, and rate of perceived exertion (RPE)³. Predominantly concentric strength exercises trigger a transient immunomodulatory response, increasing total white blood cells and circulating neutrophils 2 hours post-exercise³. In contrast, a 1:5 work-to-rest concentric protocol led to a decrease in circulating lymphocytes 2 hours after the session³. Predominantly eccentric resistance sessions did not alter circulating Th1 or Th2 cytokines or soluble tumor necrosis factor receptors (sTNFR1, sTNFR2) 2 hours post-exercise, indicating that the acute immune response depends on the specific type of muscle action performed³. These are transient acute-exercise responses, and their clinical implications for cardiovascular or immune outcomes remain uncertain³.

Public Health Guidelines and Clinical Translation

The clinical and epidemiological evidence has driven a major shift in physical activity guidelines from leading health organizations, including the World Health Organization (WHO), the American Heart Association (AHA), the American College of Sports Medicine (ACSM), and the Centers for Disease Control and Prevention (CDC)¹⁸. Current guidelines recommend that adults accumulate at least 150 to 300 minutes of moderate-intensity (or 75 to 150 minutes of vigorous-intensity) aerobic physical activity per week¹⁸. Crucially, all these organizations emphasize that aerobic exercise should be combined with moderate-to-high-intensity muscle-strengthening activities involving all major muscle groups on ≥2 days per week¹⁸.

To translate these recommendations into practical clinical targets, health professionals can utilize the “talk test” to help patients monitor exercise intensity without specialized equipment¹⁹. During moderate-intensity activity, an individual should be able to talk but not sing¹⁹. During vigorous-intensity activity, the individual will breathe heavily and will not be able to speak more than a few words without pausing for breath¹⁹.

For patients initiating a program, clinical counseling should focus on a gradual progression¹⁹. This is particularly important for special populations, such as individuals with spinal cord injury (SCI), for whom published exercise guidelines note that a greater relative intensity and duration of physical activity may be needed to achieve cardiometabolic benefit; clinicians should apply population-specific guidance rather than extrapolating directly from general adult targets¹⁸. Rather than prescribing rigid training regimens, clinicians should encourage patients to build sustainable movement habits, starting with simple bodyweight exercises—such as modified pushups, planks, and squats—and progressing to resistance bands or free weights as capacity improves⁹. The ultimate clinical goal is to help patients establish consistent, long-term movement patterns that integrate both aerobic and resistance modalities while actively reducing prolonged sedentary sitting throughout the day¹.

Broader Clinical Applications

Beyond 一次予防一次予防とは、これまでに心臓発作や脳卒中を起こしたことのない人に対して治療を行い、最初の発作を防ぐことです。., resistance training is relevant across several clinical domains, although the strength of evidence varies by outcome. Meta-analyses of randomized trials indicate that resistance training produces modest reductions in resting blood pressure—on the order of roughly 3 to 5 mmHg systolic and 2 to 3 mmHg diastolic, with larger effects generally seen in hypertensive individuals—which are clinically meaningful at a population level²⁰. In people with, or at risk for, type 2 diabetes, resistance training is associated with improved insulin sensitivity and modest reductions in HbA1c, typically as part of a combined-exercise approach⁹. Resistance training is now an established component of contemporary 心臓リハビリテーション心臓発作などの心疾患の発症後に処方される、運動、教育、生活習慣の改善を組み合わせた医学的管理下で行われるプログラムであり、心血管機能を改善し、将来の発作のリスクを軽減することを目的としている。. after myocardial infarction, coronary バイパス手術バイパス手術では、体の他の部位から健康な血管を採取し、それを使用して、ひどく閉塞した冠動脈の周囲に血液を迂回させます。., or percutaneous coronary intervention, and is incorporated into exercise-based management of selected patients with stable 心不全心不全とは、心臓が体の要求を満たすのに十分なほど血液を送り出せない状態を指します。心不全という名前は誤解を招きやすいですが、心臓が停止したという意味ではありません。., where it is used chiefly to restore muscular strength and functional capacity; the American Heart Association, the American Association of Cardiovascular and Pulmonary Rehabilitation, and the American College of Sports Medicine recommend progressive resistance exercise following appropriate aerobic conditioning and medical evaluation⁹. In older adults, resistance training is a first-line countermeasure against サルコペニアSarcopenia is the progressive loss of muscle mass and strength that comes with age. and its downstream consequences—reduced mobility, falls, and loss of independence—and preserves lean mass, grip strength, gait speed, chair-rise performance, and balance, the major functional endpoints in geriatric care⁹. Resistance and other weight-bearing training also help maintain bone mineral density, attenuate age-related bone loss, and thereby contribute to reducing osteoporosis and fracture risk, a benefit of particular importance in older women⁹. Across these domains, resistance training is best positioned as a complement to—rather than a replacement for—aerobic exercise and guideline-based medical therapy⁹.

Taken together, the current evidence supports resistance training as a fundamental component of cardiovascular prevention. Although the strongest evidence for long-term cardiovascular events remains observational, randomized trials consistently show improvements in multiple established cardiovascular risk factors. Accordingly, contemporary guidelines recommend resistance exercise as a complement to—not a replacement for—aerobic exercise, healthy nutrition, smoking cessation, and evidence-based medical therapy⁹.

参考文献

1. Zhang T, Zhang Y, Lee DH, et al. Resistance Training, Aerobic Activity, Television Viewing, and Risk of Major Cardiovascular Events in U.S. Women. J Am Coll Cardiol. Published online May 25, 2026. doi:10.1016/j.jacc.2026.04.036
2. Zhang Y, Lee DH, Rezende LFM, Ma Y, Giovannucci E. Long-term resistance training with all-cause and cause-specific mortality: assessing dose-response and joint associations with aerobic physical activity. Br J Sports Med. 2026;60(12):874-883. Published 2026 Jun 12. doi:10.1136/bjsports-2025-110503
3. Fortunato AK, Pontes WM, De Souza DMS, et al. Strength Training Session Induces Important Changes on Physiological, Immunological, and Inflammatory Biomarkers. J Immunol Res. 2018;2018:9675216. Published 2018 Jun 26. doi:10.1155/2018/9675216
4. Kamada M, Shiroma EJ, Buring JE, Miyachi M, Lee IM. Strength Training and All-Cause, Cardiovascular Disease, and Cancer Mortality in Older Women: A Cohort Study. J Am Heart Assoc. 2017;6(11):e007677. Published 2017 Oct 31. doi:10.1161/JAHA.117.007677
5. Jurik R, Żebrowska A, Stastny P. Effect of an Acute Resistance Training Bout and Long-Term Resistance Training Program on Arterial Stiffness: A Systematic Review and Meta-Analysis. J Clin Med. 2021;10(16):3492. Published 2021 Aug 7. doi:10.3390/jcm10163492
6. Schroeder EC, Franke WD, Sharp RL, Lee DC. Comparative effectiveness of aerobic, resistance, and combined training on cardiovascular disease risk factors: A randomized controlled trial. PLoS One. 2019;14(1):e0210292. Published 2019 Jan 7. doi:10.1371/journal.pone.0210292
7. Lee DC, Brellenthin AG, Lanningham-Foster LM, Kohut ML, Li Y. Aerobic, resistance, or combined exercise training and cardiovascular risk profile in overweight or obese adults: the CardioRACE trial. Eur Heart J. 2024;45(13):1127-1142. doi:10.1093/eurheartj/ehad827
8. Alemayehu A, Teferi G. Effectiveness of Aerobic, Resistance, and Combined Training for Hypertensive Patients: A Randomized Controlled Trial. Ethiop J Health Sci. 2023;33(6):1063-1074. doi:10.4314/ejhs.v33i6.17
9. Paluch AE, Boyer WR, Franklin BA, et al. Resistance Exercise Training in Individuals With and Without Cardiovascular Disease: 2023 Update: A Scientific Statement From the American Heart Association. Circulation. 2024;149(3):e217-e231. doi:10.1161/CIR.0000000000001189
10. Lan Y, Wu R, Feng Y, et al. Effects of Exercise on Arterial Stiffness: Mechanistic Insights into Peripheral, Central, and Systemic Vascular Health in Young Men. Metabolites. 2025;15(3):166. Published 2025 Mar 1. doi:10.3390/metabo15030166
11. Zhang Y, Zhang YJ, Ye W, Korivi M. Low-to-Moderate-Intensity Resistance Exercise Effectively Improves Arterial Stiffness in Adults: Evidence From Systematic Review, Meta-Analysis, and Meta-Regression Analysis. Front Cardiovasc Med. 2021;8:738489. Published 2021 Oct 11. doi:10.3389/fcvm.2021.738489
12. Figueroa A, Okamoto T, Jaime SJ, Fahs CA. Impact of high- and low-intensity resistance training on arterial stiffness and blood pressure in adults across the lifespan: a review. Pflugers Arch. 2019;471(3):467-478. doi:10.1007/s00424-018-2235-8
13. García-Mateo P, García-de-Alcaraz A, Rodríguez-Peréz MA, Alcaraz-Ibáñez M. Effects of Resistance Training on Arterial Stiffness in Healthy People: A Systematic Review. J Sports Sci Med. 2020;19(3):444-451. Published 2020 Aug 13.
14. Silva JG, Rodrigues LF, Torres T, Improta-Caria AC, Oliveira EM, Fernandes T. Resistance training and cardiovascular health: epigenetic regulation. Front Physiol. 2026;16:1701689. Published 2026 Jan 15. doi:10.3389/fphys.2025.1701689
15. Zhang Y, Qiu Y. Exercise-Induced Myokines in Obesity-Related Metabolic Disorders and Cardiovascular Protection: A Narrative Review. Sports (Basel). 2026;14(5):212. Published 2026 May 21. doi:10.3390/sports14050212
16. He Z, Tian Y, Valenzuela PL, et al. Myokine Response to High-Intensity Interval vs. Resistance Exercise: An Individual Approach. Front Physiol. 2018;9:1735. Published 2018 Dec 3. doi:10.3389/fphys.2018.01735
17. Ataeinosrat A, Saeidi A, Abednatanzi H, et al. Intensity Dependent Effects of Interval Resistance Training on Myokines and Cardiovascular Risk Factors in Males With Obesity. Front Endocrinol (Lausanne). 2022;13:895512. Published 2022 Jun 10. doi:10.3389/fendo.2022.895512
18. Bull FC, Al-Ansari SS, Biddle S, et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med. 2020;54(24):1451-1462. doi:10.1136/bjsports-2020-102955
19. Piercy KL, Troiano RP, Ballard RM, et al. The Physical Activity Guidelines for Americans. JAMA. 2018;320(19):2020-2028. doi:10.1001/jama.2018.14854
20. Cornelissen VA, Fagard RH, Coeckelberghs E, Vanhees L. Impact of resistance training on blood pressure and other cardiovascular risk factors: a meta-analysis of randomized, controlled trials. Hypertension. 2011;58(5):950-958. doi:10.1161/HYPERTENSIONAHA.111.177071