疲勞與運動營養增補劑

Fatigue and Nutritional Ergogenic Aids

程一雄(I-Shiung Cheng) ； 郭家驊(Chia-Hua Kuo)

《大專體育學刊》 19卷3期 (2017/09) Pp. i-vi

https://doi.org/10.5297/ser.1903.editorial

摘要

運動引起的肌肉痠痛與發炎，為疲勞感的主要來源，通常伴隨體能下降。營養增補劑指正常飲食以外用來增強體能的口服補充品。服用哪些營養增補劑可以減少運動過程疲勞或縮短運動後肌肉痠痛時間以增強體能，為當前熱門的體育議題。評估運動疲勞並不適合用血乳酸濃度增加來斷定，應測量體能才能直接證明疲勞程度。只要氧氣供應充分，運動後乳酸很快速地由肌肉移除，血乳酸通常在運動後一小時內即返回運動前濃度。長時間耐力運動過程肌肉肝醣耗盡是疲勞產生的主因，但此時乳酸產出並不會增加（因乳酸來自葡萄糖的無氧代謝），因此無論是運動過程中的疲勞與運動後兩至三天後的延遲性肌肉疲勞疼痛的現象都不太可能是源於乳酸堆積。此外，肌肉收縮過程所產生的乳酸流經血液經過Cori cycle和糖質新生作用機制可提供肌肉外組織（例如心臟與肝腎）額外的能源來產生ATP，有些學者反而認為乳酸是正常人體延遲運動疲勞的重要機制(Nielsen, de Paoli, & Overgaard, 2001)。肌肉發炎是運動後肌肉疲勞疼痛與機能下降的主要原因。不過，肌肉痠痛現象也是保護身體的一種預警機制(McHugh, 2003)，可提醒身體適度休息，以利恢復過程順利進行細胞汰舊換新。受試者在執行單次60分鐘75%最大攝氧量腳踏車運動後，自由基與細胞發炎激素介白素TNF-Alpha、IL-1ß (interleukin-1ß, IL-1ß)、IL-6 (interleukin-6, IL-6)明顯增加，同時在24小時後肌酸激酶 (creatinine kinase, CK)值也明顯升高。自由基與IL-6有助於受傷組織動員血液中的幹細胞與活化肌肉內的衛星細胞(satellite cells)，進行肌肉細胞新生，且係透過一氧化氮自由基訊息傳遞機制(Tidball, 2017)，對於肌肉恢復扮演重要角色。列舉幾個營養增補劑研究供讀者參考：Shimomura et al. (2010)的研究中證明蹲舉運動前補充支鏈氨基酸可以有效地預防或降低運動引起肌肉疼痛，也能改善運動後續肌力下降的現象，同一時間發炎指標明顯上升的程度降低；高強度離心運動前同時食用支鏈胺基酸(branched chain amino acid, BCAA)與牛磺酸(taurine)可以延緩肌肉疼痛及損傷程度(Ra et al., 2013)；運動前石榴汁、β-羥基-β-甲基丁酸(Beta-hydroxy-Beta-methylbutyrate, HMB)或肌酸補充也有類似效果(Pimentel et al., 2011)。不同補充時間點，如運動後優質蛋白質飲食 或者是維生素C都有降低肌肉疼痛效果(Thompson et al., 2003)。補充維生素C中和發炎過程產生的自由基對訓練後耐力體能增加反而有害(Gomez-Cabrera et al., 2008)。雖然魚油有很好的抗氧化和抗發炎效果，離心運動前魚油補充沒有減緩肌肉疼痛效果(Gray, Chappell, Jenkinson, Thies, & Gray, 2014)。上述營養補充劑研究部分成果是沒有重複性(replicated)實驗的支持，因此尚需要更多研究成果支持。年齡及人體荷爾蒙環境可影響訓練後肌肉量與肌力發展，尤其合成性荷爾蒙如睪固醇(testosterone)、生長激素(growth hormone)、胰島素成長因子(insulin growth factor-1, IGF- 1)與胰島素(insulin)濃度可隨年齡下降。高齡者肌少症(sarcopenia)指肌肉量與肌力下降現象，發生的原因和機轉尚未完全被清楚地了解。營養補充配合重量訓練對抗肌少症為重要介入手段 (Paddon-Jones & Rasmussen, 2009)。肌少症通常發生於背景發炎指數較高(systemic inflammation)、性荷爾蒙與生長激素及IGF-1下降之老人。因此，抗發炎的營養補充選擇配合阻力運動訓練被視為未來可以預防和改善衰弱及肌少症的產品開發方向。過去人體研究證明阻力運動可改善肌肉量與肌力(Liu & Latham, 2011)，Koopman et al. (2006)研究指出正常碳水化合物額外添加蛋白質或補充白氨酸使肌肉合成的速率加快。在高齡化社會，抗肌少症的運動營養策略是值得研究的議題。另外在運動競技上，有哪些特殊營養增補方法可縮短發炎修復時間，應可有效地提升選手運動競賽成績，在未來運動科學應用上將有很大的發展空間。

並列摘要

Exercise-induced inflammation is the major source of delayed-onset muscle soreness and subjective fatigue feeling, which is accompanied with decreased performance. Nutritional ergogenic aids are defined as specific oral supplements in addition to the major nutrients that can delay inflammation process to improve performance recovery. Therefore, supplementation of ergogenic aids is becoming an attractive area in sports science. Designing of nutritional ergogenic aids is typically involved with evaluation of fatigue. Plasma lactate concentration may not be a good marker to demonstrate the level of fatigue during prolonged exercise or after exercise. Instead, lactate can simply reflects the level of anaerobic metabolism of glycogen. During prolonged exercise, muscle glycogen is gradually depleted; therefore the source of lactate production decreases. Furthermore, oxygen supply recovers immediately after exercise, which means lactate dropped rapidly after exercise in only 1 hour, while muscle fatigue feeling and underperformance are still persistent. Therefore, muscle soreness peaks 2 ~ 3 days after exercise is not related to accumulation of lactate. Besides, lactate produced during exercise will be recycled by the Cori cycle in the heart, liver, and kidney for ATP resynthesis. Lactate is essential for the delayed fatigue during exercise (Nielsen, de Paoli, & Overgaard, 2001). As aforementioned, inflammation is the major cause of muscle fatigue and underperformance. Nevertheless, this mechanism should be regarded as a protective approach (McHugh, 2003), by reminding the brain to lower the challenge to muscle which will allow better recovery by regenerating new cells after damage induced by exercise. Oxidative stress and inflammatory cytokines (TNF-α, IL-1ß, IL-6) increase significantly together with elevated creatine kinase levels 24 hours following 1 hour cycling at 70% VO_(2max). Free radicals and IL-6 are essential for stem cell recruitment into damage site for cell regeneration via nitric oxide dependent mechanism (Tidball, 2017). In this short article, we exemplify some important nutritional ergogenic supplements. Branched chain amino acid (BCAA) has been demonstrated to lower muscle soreness, inflammation, and loss of strength induced by resistance exercise (Shimomura et al., 2010). Combination of BCAA and Taurine provides similar benefit (Ra et al., 2013). Beta-hydroxy-Beta-methylbutyrate (HMB) and creatine monohydrate have also been reported to have the same effects (Pimentel et al., 2011). Post-exercise protein and vitamin C supplementation has been shown to lower muscle soreness (Thompson et al., 2003). However, high dose vitamin C has been reported to eradicate the training effect on endurance performance (Gomez-Cabrera et al, 2008). Furthermore, fish oil with antioxidant nature has no beneficial effect on exercise-induced muscle soreness (Gray, Chappell, Jenkinson, Thies, & Gray, 2014). We must therefore note that reproducibility of the results should be taken into account, before making suggestion to users. Age and anabolic hormone availability can also influence the feeling of fatigue, as those are essential for muscle development. In particular, testosterone, growth hormone, insulin growth factor-1 (IGF-1) and insulin are altered with aging. These factors are crucial in sarcopenic population among elderliness. Sarcopenia denoted by loss of muscle mass and strength is also a target of ergogenic supplement. There is little doubt that nutrition is essential in treating sarcopenia among elderlies (Paddon-Jones & Rasmussen, 2009). Sarcopenia is associated with systemic inflammation together with decreased testosterone, growth hormone, IGF-1 and insulin concentrations. Therefore, designing nutritional supplements for weight training should also consider whether it alters aforementioned humeral factors. It is well documented that weight training improves muscle mass and strength (Liu & Latham, 2011). In this context, protein supplementation should always be included together with sufficient carbohydrate to increase muscle protein synthesis via insulin (Koopman et al., 2006). In the increasingly aging society, nutritional ergogenic supplementation that prevents loss of muscle mass and strength becomes an area of focus in sports nutrition. Anti-inflammatory ergogenic aids by confining the inflammation process will be a practical approach for designing the performance enhancing products for athletes. So far, still there is a big space for the improvement in the area of sports nutrition for both directions.

參考文獻

Tidball, J. G. (2017) Regulation of muscle growth and regeneration by the immune system. Nature Reviews Immunology, 17(3), 165-178.

Gomez-Cabrera, M. C., Domenech, E., Romagnoli, M., Arduini, A., Borras, C., Pallardo, F. V., ... Viña, J. (2008). Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance. The American Journal of Clinical Nutrition, 87(1), 142-149.

Gray, P., Chappell, A., Jenkinson, A. M., Thies, F., & Gray, S. R. (2014). Fish oil supplementation reduces markers of oxidative stress but not muscle soreness after eccentric exercise. International Journal of Sport Nutrition and Exercise Metabolism, 24(2), 206-214.

Koopman, R., Verdijk, L., Manders, R. J., Gijsen, A. P., Gorselink, M., Pijpers, E., ... van Loon, L. J. (2006). Coingestion of protein and leucine stimulates muscle protein synthesis rates to the same extent in young and elderly lean men. The American Journal of Clinical Nutrition, 84(3), 623-632.

Liu, C. J., & Latham, N. (2011). Can progressive resistance strength training reduce physical disability in older adults? A meta-analysis study. Disability and Rehabilitation, 33(2), 87-97.