Effects of bilateral or unilateral lower body resistance exercises on markers of skeletal muscle damage

Acute effects of combined isometric and plyometric conditioning activities on sports performance and tendon stiffness in female volleyball players

This study aimed to compare the effects of bilateral and unilateral conditioning activities (CA; combined isometric and plyometric) on countermovement jump performance, modified t-agility test, Achilles tendon stiffness and skin surface temperature. Thirteen female semi-professional volleyball players performed two CAs in random order: 1) bilateral isometric half back squats followed by bilateral drop jumps (BI-CA); and 2) unilateral isometric half back squats followed by unilateral drop jumps (UNI-CA). To assess the effects of CAs, countermovement jump, modified t-agility test, Achilles tendon stiffness and skin surface temperature measurements were performed 5 min before and 6 min after the CA. Both CAs significantly increased thigh skin surface temperature from pre- to post-CA (BI-CA, p < 0.001; effect size [ES] = 1.41 and UNI-CA, p = 0.001; ES = 1.39) but none of them influenced modified t-agility test time (interaction: p = 0.338, main effect of time: p = 0.121 and condition: p = 0.819). The countermovement jump height and modified reactive strength index significantly increased from pre-to post-CA during the BI-CA condition (p = 0.003, ES = 0.45, and p = 0.008, ES = 0.48) but not for UNI-CA (p = 0.061, ES = 0.18 and p = 0.065, ES = 0.26). No significant impact has been found for countermovement depth (interaction: p = 0.054, main effect of time: 0.097, and condition: p = 0.41) as well as for contraction time (interaction: p = 0.536, main effect of time: p = 0.224, and condition: p = 0.807). Moreover, stronger and weaker limb CMJ relative peak force significantly decreased from pre-to post-CA (p = 0.014, ES = −0.31, and p = 0.027, ES = −0.26; respectively) during UNI-CA condition but not for BI-CA (p = 0.096, ES = 0.23, and p = 1.41, ES = 0.18). The stronger and weaker limb Achilles tendon stiffness significantly increased from pre-to post-CA during the UNI-CA condition (p = 0.013, ES = 0.60 and p < 0.001, ES = 0.79; respectively) but not for BI-CA (p = 0.66; ES = 0.15 and p = 0.265; ES = 0.42). Furthermore, the post-CA stronger limb Achilles tendon stiffness during the UNI-CA was significantly higher than that noted during the BI-CA (p = 0.006, ES = 0.7). The present study showed that combined isometric and plyometric bilateral CA effectively improved the countermovement jump but did not enhance the t-agility test performance. These findings indicate that exercise combinations could effectively produce a post-activation performance enhancement effect but should replicate the following explosive task as much as possible.

Combination of Treadmill Aerobic Exercise with Bifidobacterium longum OLP-01 Supplementation for Treatment of High-Fat Diet-Induced Obese Murine Model

INTRODUCTION

Obesity, which can result from disease, genetics, nutrition, lifestyle, and insufficient physical activity, substantially increases an individual's risk of complications and comorbidities. Exercise can be an effective strategy for achieving an energy balance and physiological fitness as part of obesity management. Additionally, probiotics, which are isolated from food and the environment, are being rapidly developed and have functional benefits for mitigating various metabolic dysfunctions associated with obesity. The potentially positive physiological and functional effects of exercise, probiotics, and exercise combined with probiotics should be elucidated in a model of diet-induced obesity.

METHODS

Bifidobacterium longum subsp. longum OLP-01 (OLP-01) was isolated from an elite Olympic-level athlete who exhibited physiological adaptations to peripheral fatigue caused by exercise training. In this current study, ICR strain mice were fed a high-fat diet (HFD) for 4 weeks to replicate an obesity model. The mice were divided into 5 groups according to the diet administered: control with normal diet, only HFD, HFD + exercise, HFD + OLP, and HFD + exercise + OLP groups. They were administered the probiotic and/or treadmill exercise training for 5 weeks, and their growth curve, physical activity, physiological adaptation, biochemical parameters, body composition, and glucose tolerance were assessed.

RESULTS

Compared with only exercise or only probiotics, a combination of probiotics and exercise significantly improved the weight, glucose tolerance, fat composition, and exercise-related oxidative stress of mice. Regular and programmed exercise with sufficient rest may be crucial to obesity improvement, and a combination of probiotics and exercise may synergistically assist obesity management and health promotion.

CONCLUSION

OLP-01 probiotics combined with exercise training can be employed as a strategy for treating obesity. However, the exact regulatory mechanisms underlying this effect, possibly involving microbiota and associated metabolites, warrant further investigation.

Changes in Salivary Levels of Creatine Kinase, Lactate Dehydrogenase, and Aspartate Aminotransferase after Playing Rugby Sevens: The Influence of Gender

Rugby sevens is characterised by continuous exertion and great physical contact per unit of time, leading to muscle damage. It is important to identify markers that can quantify muscle damage in order to improve recovery strategies. The objective of this study was to evaluate the release dynamics of muscle damage markers creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) in saliva samples when playing rugby sevens, analysing the influence of gender, during the rugby sevens university championship of Spain. The total sample included 27 athletes, divided into two teams of 14 men and 13 women between 18 and 31 years of age. CK, LDH, and AST were quantified from salivary samples collected from each athlete before and after three rugby sevens matches. The modified Borg scale of perceived exertion was also used after each match. When the results were analysed globally, there were no differences in CK and LDH before and after any match, but AST did show differences after two days of completing all matches. In terms of gender, the three enzymes showed different responses in men and women. Regarding the Borg scale, there were only significant differences between men and women after completing all mataches, with a greater perceived exertion in women. Based on our results, it can be stated that that serial matches of rugby sevens can cause changes of different magnitude in AST, CK and LDH activities in saliva, with AST showing the most significant variations and these changes are more pronounced in men than in women.

The Effect of Orally Dosed Levagen+™ (palmitoylethanolamide) on Exercise Recovery in Healthy Males-A Double-Blind, Randomized, Placebo-Controlled Study

The aim of this study was to evaluate the effect of palmitoylethanolamide (PEA), a cannabimimetic compound and lipid messenger, on recovery from muscle damaging exercise. Twenty-eight healthy young male participants attended the laboratory four times on subsequent days. In the first visit, baseline characteristics were recorded before participants were randomized to consume either liquid PEA (167.5 mg Levagen+ with 832.5 mg maltodextrin) or a matched placebo (1 g maltodextrin) drink. Leg press exercise consisted of four sets at 80% of one repetition maximum followed by a performance set. Muscle soreness, thigh circumference, blood lactate concentration, biomarkers of muscle damage and inflammation, and transcription factor pathways were measured pre- and immediately post-exercise and again at 1, 2, 3, 24, 48, and 72 h post-exercise. The leg press exercise increased (p < 0.05) blood lactate concentration and induced muscle damage as evidenced by increased muscle soreness, thigh circumference, biomarkers of muscle damage, and concentrations of tumor necrosis factor-α. PEA reduced (p < 0.05) myoglobin and blood lactate concentrations and increased protein kinase B phosphorylation following exercise. Taken together, these results indicate PEA supplementation may aid in muscle recovery from repeat bouts of exercise performed within a short duration by reducing myoglobin and lactate concentration.

Basal-bolus or premixed? Shedding light on optimal insulin regime for type 1 diabetes

In this issue of the Biomedical Journal, we highlight original research that will help to guide the choice of insulin administration regimes for children with type 1 diabetes. We also investigate whether a common medication for attention deficit/hyperactivity disorder worsens sleep problems among these children, and discover a new approach to maximize the lifetime of a fragile piece of surgical equipment.