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.
Highlights
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)
Signifi-cant time effects were found for VO2, Creatine kinase (CK), and SOR while no significant time effect was found for perceived exertion (PE)
A downhill walking (DW) training program with progressively increasing load can lead to significant increases on EIMD markers
Summary
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). 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. 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
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