Trunk muscle endurance, strength and flexibility in rural subsistence farmers and urban industrialized adults in western Kenya
Trunk muscle endurance, strength and flexibility in rural subsistence farmers and urban industrialized adults in western Kenya.
Am J Hum Biol. 2021.
https://gyazo.com/7bd72deef278965b27a05205744ca4da
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Objectives High trunk muscle endurance, muscle strength, and moderate flexibility reportedly help maintain musculoskeletal health, but there is evidence for tradeoffs among these variables as well as sex differences in trunk muscle endurance and strength. To test if these observations extend similarly to both men and women in nonindustrial and industrial environments, we investigated intra‐individual associations and group and sex differences in trunk muscle endurance, strength, and flexibility among 74 (35 F, 39 M; age range: 18–61 years) adults from the same Kalenjin‐speaking population in western Kenya. We specifically compared men and women from an urban community with professions that do not involve manual labor with rural subsistence farmers, including women who frequently carry heavy loads. Methods Trunk muscle endurance, strength, and flexibility were measured with exercise tests and electromyography (EMG). Results We found a positive correlation between trunk extensor strength and endurance (R = .271, p ≤ .05) and no associations between strength or endurance and flexibility. Rural women had higher trunk extensor and flexor endurance, EMG‐determined longissimus lumborum endurance, and trunk extensor strength than urban women (all p ≤ .05). Rural women had higher trunk extensor and flexor endurance than rural men (both p ≤ .05). Urban women had lower trunk flexor and extensor endurance than urban men (both p ≤ .01). Conclusions High levels of physical activity among nonindustrial subsistence farmers, particularly head carrying among women, appear to be associated with high trunk muscle endurance and strength, which may have important benefits for helping maintain musculoskeletal health. 目的：高い体幹筋の持久力、筋力および適度な柔軟性は、筋骨格の健康を維持するのに役立つと報告されているが、これらの変数間（体幹筋の持久力と筋力）のトレードオフおよび性差にはエビデンスがある。これらの観察結果が非工業化環境と工業化環境の男性と女性の両方に同様に及ぶかどうかを検証するために、ケニア西部の同じカレンジン語を話す集団の74名（女性35名 、男性39名、年齢範囲：18〜61歳）の成人の体幹筋の持久力、筋力、柔軟性における個人内の関連性とグループおよび性差を調査した。具体的には、都市部の肉体労働を伴わない職業の男性と女性を、重い荷物を頻繁に運ぶ女性を含む農村の自給自足農民と比較した。 方法：体幹筋の持久力、筋力、柔軟性は、運動テストと筋電図（EMG）で測定された。 結果：体幹の伸展筋の筋力と持久力には正の相関があり（R=0.271,p≤0.05）、筋力または持久力と柔軟性には相関がなかった。農村部の女性は、都市部の女性よりも体幹の伸展筋と屈曲筋の持久力、EMGから求めた最長筋（脊柱起立筋の一部）の持久力、および体幹伸展筋の筋力が高かった（すべてp≤0.05）。農村部の女性は男性よりも、体幹伸転筋と屈曲筋の持久力が高かった（両方ともp≤0.05）。都市部の女性は男性よりも、体幹屈曲筋と伸展筋の持久力が低かった（両方ともp≤.01）。結論：非工業的自給自足農民の高レベルの身体活動、特に女性の頭上運搬は、高い体幹筋の持久力と筋力に関連してそうであり、これは筋骨格の健康を維持するのに重要な利益があるかもしれない。