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The aim of this study was to investigate the effects of different resistance training (RT) volumes on MMP activity in skeletal muscle, visceral adipose tissue and circulation. 21 Wistar rats were randomly divided into 3 groups (n=7 per group): sedentary control (SC); RT with 4 ladder climbs (RT-4; 50, 75, 90 and 100% of their maximal carrying capacity) and RT with 8 ladder climbs (RT-8 with 2 sets for each load). The 8-week RT consisted of climbing a 1.1-m vertical ladder with weights secured to the animals' tails. MMP-2 and -9 activity were analyzed by zymography. RT-8 displayed higher active MMP-2 activity as compared with SC and RT-4 in skeletal muscle (p<0.05). There was no significant difference between groups for pro and intermediate-MMP-2 activity in visceral adipose tissue, while RT-8 presented lower active MMP-2 activity as compared with SC (p<0.05). Plasma pro and active MMP-2 and MMP-9 activity was lower in RT-8 as compared with RT-4 (p<0.05). These results suggest that higher volume RT up-regulates MMP-2 activity in skeletal muscle, while down-regulating MMP-2 in visceral adipose tissue. Moreover, it induces a decrease of MMP-2, 9 activity in circulation. Different tissue and circulatory MMP responses to RT may result in specific remodeling., (© Georg Thieme Verlag KG Stuttgart · New York.)

This study investigated the effects of 5 and 15°C cold-water immersion on recovery from exercise resulting in exercise-induced muscle damage. 42 college-aged men performed 5×20 drop-jumps and were randomly allocated into one of 3 groups: (1) 5°C; (2) 15°C; or (3) control. After exercise, individuals from the cold-water immersion groups had their lower limbs immerged in iced water for 20 min. Isometric knee extensor torque, countermovement jump, muscle soreness, and creatine kinase were measured before, immediately after, 24, 48, 72, 96 and 168 h post-exercise. There was no between-group difference in isometric strength recovery (p=0.73). However, countermovement jump recovered quicker in cold-water immersion groups compared to control group (p<0.05). Countermovement jump returned to baseline after 72 h in 15°C, 5°C group recovered after 96 h and control did not recovered at any time point measured. Also, creatine kinase returned to baseline at 72 h and remained stable for all remaining measurements for 15°C group, whereas remained elevated past 168 h in both 5°C and control groups. There was a trend toward lower muscle soreness (p=0.06) in 15°C group compared to control at 24 h post-exercise. The result suggests that cold-water immersion promote recovery of stretch-shortening cycle performance, but not influence the recovery of maximal contractile force. Immersion at warmer temperature may be more effective than colder temperatures promoting recovery from strenuous exercise., (© Georg Thieme Verlag KG Stuttgart · New York.)

Matrix metalloproteinases (MMPs) are crucial to the development and maintenance of healthy tissue and are mainly involved in extracellular matrix (ECM) remodeling of skeletal muscle. This study evaluated the effects of chronic allergic airway inflammation (CAAI), induced by ovalbumin, and aerobic training in the MMPs activity in mouse diaphragm muscle. Thirty mice were divided into 6 groups: 1) control; 2) ovalbumin; 3) treadmill trained at 50% of maximum speed; 4) ovalbumin and trained at 50%; 5) trained at 75%; 6) ovalbumin and trained at 75%. CAAI did not alter MMPs activities in diaphragm muscle. Nevertheless, both treadmill aerobic trainings, associated with CAAI increased the MMP-2 and -1 activities. Furthermore, MMP-9 was not detected in any group. Together, these findings suggest an ECM remodeling in diaphragm muscle of asthmatic mice submitted to physical training. This result may be useful for a better understanding of functional significance of changes in the MMPs activity in response to physical training in asthma.