Monitoring muscle damage markers during a four-week downhill walking exercise program

Motriz, Rio Claro, v.19 n.4, p.703-708, Oct./Dec. 2013 DOI: http://dx.doi.org/xx.xxxx/xxxx-xxxx.xxxxxxxxxxxxx Original article Monitoring muscle damage markers during a four-week downhill walking exercise program Leonardo Coelho Rabello de Lima Thiago Pires de Oliveira Felipe Bruno Dias de Oliveira Claudio de Oliveira Assumpção Camila Coelho Greco Benedito Sérgio Denadai São Paulo State University at Rio Claro, Brazil Abstract—Eccentric-based exercise is known to induce muscle damage (MD). The purpose of this study was to investigate effect of downhill walking (DW) sessions on MD and aerobic markers in young adults. Eight male subjects were submitted to a 4-week DW periodized exercise program. Subjects’ soreness (SOR) was assessed each training day. Serum creatine quinase activity (CK) was collected before the first training session, and at the end of each of the four weeks. Oxygen uptake (VO2) and perceived exertion (PE) were assessed during the last training session every week. Increases in SOR were found only at the third and fourth training days. Increased CK concentration was found at the third training week. No significant increases in VO2 and PE were found throughout the program. We concluded that DW sessions elicit significant MD, but not enough to impair it in further sessions. Therefore, DW can be used as a training protocol following proper periodization. Keywords: downhill walking, muscle damage, training Resumo—“Monitoramento de marcadores de dano muscular durante um programa de quatro semanas de treinamento de caminhada em declive.” Exercícios excêntricos costumam induzir dano muscular (DM). O objetivo deste estudo foi investigar respostas aeróbias e de DM a sessões de caminhada em declive (CaED) em adultos. Oito voluntários realizaram um programa periodizado de treinamento de CaED. A dor muscular (DMIT) foi coletada durante todos os dias de treinamento. A atividade sérica de creatina quinase (CK) foi coletada antes da primeira sessão e ao final das semanas 1-4. O consumo de oxigênio (VO2) e a percepção de esforço (PE) foram coletados durante a última sessão de treinamento de cada semana. Aumentos na DMIT foram identificados no terceiro e quarto dias de treinamento. Os valores de CK se apresentaram aumentados na terceira semana. Não foram identificadas diferenças nos valores obtidos de VO2 e PE. Concluímos que sessões de CaED induzem DM, porém este não afeta sessões posteriores. Portanto, a CaED pode ser utilizada como um método de treinamento, possibilitando sua periodização. Palavras-chaves: caminhada em declive, dano muscular, treinamento Resumen—“Marcadores de monitoreo de daño muscular durante un programa de cuatro semanas de entrenamiento a pie cuesta abajo.” Ejercicio excéntrico desacostumbrado es conocido por inducir daño muscular (DM). El objetivo de este estudio fue investigar las respuestas a sesiones de caminar cuesta abajo (DW) en los adultos jóvenes, la evaluación de MD y los marcadores de aeróbicos. Ocho sujetos varones fueron sometidos a un programa de ejercicios de periodización de DW de 4 semanas. El dolor de los sujetos (SOR) se evaluó todos los días de entrenamiento. Actividad de la creatina quinasa sérica (CK) se recogió antes de la primera sesión de entrenamiento, y al final de las semanas 1-4. El consumo de oxígeno (VO2) y la percepción subjetiva del esfuerzo (PE) se evaluaron durante la última sesión de entrenamiento cada semana. Los aumentos en SOR se encontraron sólo en los tercero y cuarto día de entrenamiento. El aumento de la concentración de CK se encuentra en la tercera semana de entrenamiento. No hay un aumento significativo en el VO2 y PE se encuentran en todo el programa. Llegamos a la conclusión de que las sesiones DW provocan MD significativo, pero no lo suficiente como para poner en peligro otras sesiones. Por lo tanto, DW puede ser adoptado como método de entrenamiento, permitiendo periodización adecuada. Palabras claves: descenso a pie, daño muscular, entrenamiento 703 L.C.R. Lima, T.P. Oliveira, F.B.D. Oliveira, C.O. Assumpção, C.C. Greco, & B.S. Denadai Introduction It is well established that unaccustomed exercise can lead to exercise-induced muscle damage (EIMD), especially when eccentric actions are performed at high volumes or intensities (Brenner et al., 1999; Lindstedt, LaStayo, & Reich, 2001; Clarkson & Hubal, 2002; Yu, Malm, & Thornell, 2002). Downhill running (DR), an exercise model frequently used to generate muscle damage (Byrnes et al., 1985), seems to induce EIMD by two associated mechanisms: high intensity (due to the declined surface) and high volume (due to the cyclic characteristic of running) of eccentric contractions. Indeed, several studies have demonstrated that DR can lead to strength loss, delayed-onset muscle soreness (DOMS), changes in running kinematic parameters and impairment of running economy (Chen et al., 2007; Chen, Nosaka, Lin, Chen, & Wu, 2009; Assumpção et al., 2013). Therefore, DR can be considered a highly damaging activity, which would impair further sessions if applied as training stimulus. A considerable number of studies have also investigated the effect of downhill walking (DW) on biomechanical and physiological responses. However, the majority of them did not take EIMD in consideration, assessing only biomechanical (joint kinematics, and muscle activity) (Holm, Contakos, Lee, & Jang, 2010; Hunter, Hendrix, & Dean, 2010) or cardiorespiratory intensity-related factors (oxygen uptake) (Abe et al., 2011; Minetti, Moia, Roi, Susta, & Ferretti, 2002). Evidence obtained from animal experimental models has shown that the DW training can lead to neuromuscular (Lyn & Morgan, 1994) and metabolic (Hahn et al., 2007) adaptations. In humans, few studies have analyzed the chronic effects of DW training on physical fitness. Yang, Lee, Cheng and Wang (2010) verified that four weeks of DW (-3 to -8.5% slope) training (30 minutes, at 0.63 to 0.99 km/h, 3 days per week,) was more effective than conventional therapy in improving muscle strength and gait performance in individuals with Parkinson’s disease. Gault, Clements, and Willems (2012) investigated the effects of 12 weeks of DW (-10% slope) training (30 minutes at 53 to 81% of the maximal walking speed, 3 days per week) in older adults. Although there was significant improvement in functional tests, the isokinetic strength of the knee extensors and flexors remained unaltered after the training period. In these studies, EIMD markers were not controlled. Since the exercise intensity (speed and slope) and the weekly frequency were relatively low, it is possible that the muscle damage response may have been small, allowing the volunteers to accomplish the whole training protocol. To our knowledge, no studies have investigated the effects of DW training in individuals with higher fitness levels (i.e., aerobic and strength) than those individuals in the studies mentioned earlier (Yang et al., 2010; Gault et al., 2012). Since adaptation (...truncated)