Exercise-Induced Muscle Damage after a High-Intensity Interval Exercise Session: Systematic Review.

High-intensity interval training (HIIT) is considered an effective method to improve fitness and health indicators, but its high-intensity exercises and the mechanical and metabolic stress generated during the session can lead to the occurrence of exercise-induced muscle damage. Therefore, this study aimed to describe, by means of a systematic review, the effects of a single HIIT session on exercise-induced muscle damage. A total of 43 studies were found in the Medline/PubMed Science Direct/Embase/Scielo/CINAHL/LILACS databases; however, after applying the exclusion criteria, only 15 articles were considered eligible for this review. The total sample was 315 participants. Among them, 77.2% were men, 13.3% were women and 9.5 uninformed. Their age ranged from 20.1 ± 2 to 47.8 ± 7.5 years. HIIT protocols included running with ergometers (n = 6), CrossFit-specific exercises (n = 2), running without ergometers (n = 3), swimming (n = 1), the Wingate test on stationary bicycles (n = 2), and cycling (n = 1). The most applied intensity controls were %vVO2max, "all out", MV, MAV, Vmax, and HRreserve%. The most used markers to evaluate muscle damage were creatine kinase, myoglobin, and lactate dehydrogenase. The time for muscle damage assessment ranged from immediately post exercise to seven days. HIIT protocols were able to promote changes in markers of exercise-induced muscle damage, evidenced by increases in CK, Mb, LDH, AST, ALT, pain, and muscle circumference observed mainly immediately and 24 h after the HIIT session.

Effect of Sodium Bicarbonate Supplementation on Muscle Performance and Muscle Damage: A Double Blind, Randomized Crossover Study.

Sodium bicarbonate (NaHCO3) has been used as an ergogenic substance during high-intensity exercises. Therefore, the aim of the present study was to investigate the effects of NaHCO3 supplementation on external and internal load parameters during isokinetic exercise in trained subjects. Ten subjects were tested on two occasions: after ingesting 0.3 g.kg-1 of body mass of NaHCO3 or placebo. Maximum voluntary isometric contraction was performed before and after a dynamic protocol consisting of 10 series of 10 movements of flexion/extension of the knee extensors at 120° s-1 at an interval of 60 s between series. Outcomes considered were: peak torque (isokinetic dynamometry), blood lactate and creatine concentration (CK), analysis of perceptions of effort (OMNI scale), pain (visual analog scale) and recovery (scale raging 6 to 20). Performance was assessed using peak torque values. Muscle damage was assessed prior and 24 h post exercise. The subjective perceptions of effort, pain and recovery were assessed at different times and the internal load of the session was assessed 30 min post-effort. Although significant reductions in peak torque were noted both in isometric (NaHCO3:-29.11 ± 22.95%, Placebo: -23.51 ± 15.23%; p = 0.38) and isokinetic strength (NaHCO3:-23.0 ± 13.9%, Placebo:-19.6 ± 9.1%; p = 0.09), there was no effect of supplementation on performance (p > 0.05). The blood CK concentrations (NaHCO3: pre:225.3 ± 135.9 U/L, post: 418.4 ± 318.4 U/L; Placebo: pre:238 ± 94.03 U/L, post:486 ± 336.6 U/L) increased after protocol (p = 0.005), however, without differences between conditions. In conclusion, the NaHCO3 did not attribute benefits in performance or in parameters related to the internal load of exercise.

Physical training attenuates right ventricular dysfunction in rats exposed to cigarette smoke

Abstract Aim: To evaluate the functional and morphological cardiac variables of rats exposed to chronic cigarette smoke (ECS) and to analyze the influence of exercise training on any cardiac remodeling. Methods: Male Wistar rats were assigned into four groups: control animals (C, n=10); control trained rats (CT, n=10), that underwent swimming physical training; ECS rats (E, n=10), that received the smoke of 40 cigarettes/day; and ECS plus trained rats (TE, n=10), that received the cigarette smoke plus the swimming training protocol, for 15 weeks. At the end of the experiment, the animals underwent hemodynamic measurements of the right ventricle (RV) and morphological examination. Results: There was a decrease in the body weight of E, TE and CT groups (p<0.05). RV pressure (maximum systolic, diastolic initial and end-diastolic) was increased in the E and ET groups (p <0.05), while there was a decrease in RV maximum derivative pressure, RV minimum derivative pressure (+dP/dt and -dP/dt) and systolic duration in the TE group (p <0.05). Heart rate increased in the E group (p<0.05). The lung weight/body weight ratio was higher in the TE group (p=0.008). Fluid retention was increased in the RV, left ventricle (LV) and lung of the E group (p<0.001). Conclusion: ECS caused right ventricular dysfunction, pulmonary hypertension and cardiac remodeling. Physical training attenuated the effects of ECS for heart rate responses and the morphological variables of the RV, LV, and the lung.

Multivariate linear regression analysis to evaluate multiple-set performance in active and inactive individuals

Abstract Aim: To determine how EMG, anthropometric, and psychological factors, and physical activity levels affect isokinetic peak torque performance (IPT) of multiple set exercise sessions. Methods: 20 participants (27±7 years old), classified as active (A=10) and inactive (I=10), performed 10x10:40secs of maximal unilateral knee flexions and extensions at 120o.s-1. The IPT, EMG, glucose, LDH, and lactate concentrations and perceptions of pain, effort, recovery. Results: Active volunteers showed higher muscularity (52±5 vs 47±4 cm; p<0.05), PTI (262±4 vs 185±4 Nm; p<0.05), relative lower drop in performance (14±2 vs 27±3% ; p<0.05), major MDF (83±1 vs 76±1 Hz; p<0.05), lower log -Fins5 (-12.9±0.3 vs -12.7 ± 0.3 Hz; p<0.05), smaller subjective perception of effort (14.8±0.3 vs 17.0±0.3) and higher subjective perception of recovery (14.2±0.2 vs 12.3±0.3). There was a significant interaction between relative fatigue and the number of sets (F=6.18; p<0.001). Stepwise multiple regressions revealed that subjective perception of recovery best explained the fatigue level generated in the active volunteers [fatigue level= 85.084-5255(SPR)] while for body mass was the best determinant for the inactive group [fatigue level = -21.560 +1.828(BMI)]. Conclusion: Data from the present analysis suggest that physically active individuals show higher torque development and a smaller fatigability index when compared to inactive individuals. Among the fatigue models studied, it is possible that alterations in biochemical components, psychophysiological and EMG are not sensitive to the direct influence of the fatigue dynamics protocol, both in active or inactive individuals.