Effects of static and dynamic stretching performed before resistance training on muscle adaptations in untrained men. J Strength Cond Res 35(11): 3050-3055, 2021-This study evaluated the effects of dynamic and static stretching (SS) performed before resistance training on biceps femoris hypertrophy and knee flexor strength gains in untrained young men. Forty-five untrained young men (age, 21.2 6 0.5 years; mass, 72.2 6 5.6 kg; height, 178 6 1 cm) were randomly assigned to 1 of the 3 groups: (a) 80 seconds of SS (n 5 14); (b) 80 seconds of dynamic stretching (DS, n 5 13); or (c) control group (CON, n 5 18) in which subjects performed no stretching before exercise. Both SS and DS were performed before resistance exercise. Resistance training consisted of 4 sets of 8-12 repetition maximum of seated leg curl exercise 2 days per week for 8 weeks, with a period of at least 48 hours between sessions. Unilateral biceps femoris muscle thickness (MT) and maximal isometric strength (MIS) of the knee flexors were measured 1 week before training and 1 week after the last training session. There were significant increases in MIS (SS 5 13.9 6 10.3 kgf; DS 5 10.2 6 13.1 kgf; CON 5 12.7 6 7.6 kgf; p , 0.05) and MT (SS 5 6.0 6 3.5 mm; DS 5 6.7 6 4.1 mm; CON 5 5.7 6 3.0 mm; p , 0.05) with no significant differences across groups (p . 0.05). Additionally, all groups demonstrated moderate effect sizes for MIS (1.27-1.4), and DS was the only group that had a large effect size for MT increases (DS 5 2.18; SS 5 1.35; CON 5 0.92). In conclusion, 80 seconds of SS and DS did not induce any additional muscular adaptations to resistance training in untrained young men.

The coronavirus disease 2019 (COVID-19) has spread to at least 115 countries and caused an alarming number of deaths. The current outbreak has lead authorities from many countries to adopt several protective measures, including lockdown and social distancing. Although being a reasonable measure to counteract the COVID-19 contamination, the restrictive measures have limited individual's ability to perform exercise outdoors or in gyms and similar facilities, thus raising the risks for chronic health conditions related to a sedentary lifestyle. The recent exercise recommendations to counteract the potential deleterious effects of COVID-19-related lockdown have not fully addressed resistance exercise interventions as potential home-based exercise strategies. Additionally, the following questions have been constantly raised: (1) Is training status capable of protecting an individual from COVID-19 infection?; and (2) Can a single endurance or resistance exercise session acutely increase the risks for COVID-19 infection? Therefore, the current mini review aimed to focus on these two concerns, as well as to discuss the potential use of practical blood flow restriction and no load resistance training as possible resistance exercise strategies that could be performed during the current COVID-19 pandemic.

Objective. The measurement of skin temperature using infrared thermography has gained a lot of attention in sport and science since it might be related to the recovery process following high intensity, potentially damaging exercise. This study investigated the time course of the skin temperature response and the muscle recovery status following a resistance training session involving leg press exercise. Approach. Fourteen young male college students (19.9 ± 1.7 years, 176 ± 6 cm, 66.1 ± 7.6 kg, 21.1 ± 1.8 kg.m−2) performed one session involving 10 sets, of 10 repetition maximum each (RM), of unilateral leg press 45° exercise, performed to momentary muscle failure, with 2 min rest between sets. Perceived recovery, mean and maximum thigh skin temperatures, thigh muscle thickness, maximal isometric strength, muscle soreness, and horizontal jump performance were measured pre, 24, 48, and 72 h following exercise. Main results. The exercise protocol resulted in significant reduction in isometric strength, horizontal jump performance, and perceived recovery (p < 0.05). There was also a significant (p < 0.05) increase in muscle thickness and muscle soreness. With exception of jump performance, that recovered at 48 (p > 0.05), recovery parameters did not recover up to 72 h post-exercise (p > 0.05). Surprisingly, skin temperatures were not altered throughout the entire 72 h post-exercise period (p > 0.05). No significant positive correlation was found between skin temperatures and muscle thickness. Additionally, only one out of 16 correlation coefficients showed significant (r = −0.56, p = 0.036) inverse association between skin temperature and isometric strength. Significance. In conclusion, thigh skin temperature remains unaffected up to 72 h following a leg press exercise, and the time course response of thigh skin temperature was not associated with recovery status.

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