The effects of theaflavin-enriched black tea extract on muscle soreness, oxidative stress, inflammation, and endocrine responses to acute anaerobic interval training: a randomized, double-blind, crossover study

<p>Abstract</p> <p>Background</p> <p>Muscle soreness and decreased performance often follow a bout of high-intensity exercise. By reducing these effects, an athlete can train more frequently and increase long-term performance. The purpose of this study is to examine whether a high-potency, black tea extract (BTE) alters the delayed onset muscle soreness (DOMS), oxidative stress, inflammation, and cortisol (CORT) responses to high-intensity anaerobic exercise.</p> <p>Methods</p> <p>College-age males (N = 18) with 1+ yrs of weight training experience completed a double-blind, placebo-controlled, crossover study. Subjects consumed the BTE (1,760 mg BTE·d^-1) or placebo (PLA) for 9 days. Each subject completed two testing sessions (T1 & T2), which occurred on day 7 of the intervention. T1 & T2 consisted of a 30 s Wingate Test plus eight 10 s intervals. Blood samples were obtained before, 0, 30 & 60 min following the interval sessions and were used to analyze the total to oxidized glutathione ratio (GSH:GSSG), 8-isoprostane (8-iso), CORT, and interleukin 6 (IL-6) secretion. DOMS was recorded at 24 & 48 h post-test using a visual analog scale while BTE or PLA continued to be administered. Significance was set at <it>P < 0.05</it>.</p> <p>Results</p> <p>Compared to PLA, BTE produced significantly higher average peak power (<it>P = 0.013</it>) and higher average mean power (<it>P = 0.067</it>) across nine WAnT intervals. BTE produced significantly lower DOMS compared to PLA at 24 h post test (<it>P < 0.001</it>) and 48 h post test (<it>P < 0.001</it>). Compared to PLA, BTE had a slightly higher GSH:GSSG ratio at baseline which became significantly higher at 30 and 60 min post test (<it>P < 0.002</it>). AUC analysis revealed BTE to elicit significantly lower GSSG secretion (<it>P = 0.009</it>), significantly higher GSH:GSSG ratio (<it>P = 0.001</it>), and lower CORT secretion (<it>P = 0.078</it>) than PLA. AUC analysis did not reveal a significant difference in total IL-6 response (<it>P = 0.145</it>) between conditions.</p> <p>Conclusions</p> <p>Consumption of theaflavin-enriched black tea extract led to improved recovery and a reduction in oxidative stress and DOMS responses to acute anaerobic intervals. An improved rate of recovery can benefit all individuals engaging in high intensity, anaerobic exercise as it facilitates increased frequency of exercise.</p

Genome-wide DNA methylation levels and altered cortisol stress reactivity following childhood trauma in humans

DNA methylation likely plays a role in the regulation of human stress reactivity. Here we show that in a genome-wide analysis of blood DNA methylation in 85 healthy individuals, a locus in the Kit ligand gene (KITLG; cg27512205) showed the strongest association with cortisol stress reactivity (P=5.8 � 10?6). Replication was obtained in two independent samples using either blood (N=45, P=0.001) or buccal cells (N=255, P=0.004). KITLG methylation strongly mediates the relationship between childhood trauma and cortisol stress reactivity in the discovery sample (32% mediation). Its genomic location, a CpG island shore within an H3K27ac enhancer mark, and the correlation between methylation in the blood and prefrontal cortex provide further evidence that KITLG methylation is functionally relevant for the programming of stress reactivity in the human brain. Our results extend preclinical evidence for epigenetic regulation of stress reactivity to humans and provide leads to enhance our understanding of the neurobiological pathways underlying stress vulnerability

Genetic variation and exercise-induced muscle damage: implications for athletic performance, injury and ageing.

Prolonged unaccustomed exercise involving muscle lengthening (eccentric) actions can result in ultrastructural muscle disruption, impaired excitation-contraction coupling, inflammation and muscle protein degradation. This process is associated with delayed onset muscle soreness and is referred to as exercise-induced muscle damage. Although a certain amount of muscle damage may be necessary for adaptation to occur, excessive damage or inadequate recovery from exercise-induced muscle damage can increase injury risk, particularly in older individuals, who experience more damage and require longer to recover from muscle damaging exercise than younger adults. Furthermore, it is apparent that inter-individual variation exists in the response to exercise-induced muscle damage, and there is evidence that genetic variability may play a key role. Although this area of research is in its infancy, certain gene variations, or polymorphisms have been associated with exercise-induced muscle damage (i.e. individuals with certain genotypes experience greater muscle damage, and require longer recovery, following strenuous exercise). These polymorphisms include ACTN3 (R577X, rs1815739), TNF (-308 G>A, rs1800629), IL6 (-174 G>C, rs1800795), and IGF2 (ApaI, 17200 G>A, rs680). Knowing how someone is likely to respond to a particular type of exercise could help coaches/practitioners individualise the exercise training of their athletes/patients, thus maximising recovery and adaptation, while reducing overload-associated injury risk. The purpose of this review is to provide a critical analysis of the literature concerning gene polymorphisms associated with exercise-induced muscle damage, both in young and older individuals, and to highlight the potential mechanisms underpinning these associations, thus providing a better understanding of exercise-induced muscle damage

INFLUENCE OF A WARM-UP PROTOCOL INVOLVING THE KINETIC CHAIN ON ATHLETES’ HIP AND SHOULDER ROTATIONAL ISOMETRIC STRENGTH: A PILOT STUDY

Courtney E. Weber, Jeff W. Barfield. Lander University, Greenwood, SC. Athletes are at risk for developing injuries if they do not properly stretch or partake in a warm-up prior to engaging in exercise. Previous research has found decreased rotational strength to be associated with increased injury susceptibility. Providing more information on which warm-up style best benefits the hip and shoulder rotational isometric strength could assist coaches and clinicians in preventing injuries and helping athletes compete at a competitive level. Purpose: To investigate the effects of a full body warm-up on an athlete’s hip and shoulder rotational isometric strength. Methods: Six active college-aged individuals (20.67±0.47yrs; 171.70±9.60cm; 73.12±12.77kg) agreed to participate in this study. A handheld dynamometer was used to test participant’s hip and shoulder isometric strength prior to the warm-up protocol (pre-warmup) and after the warm-up protocol (post-warmup). Shoulder rotational isometric strength was assessed in the supine position while hip rotational isometric strength was assessed in the seated position. Warm-up protocol was randomly assigned to participants upon arrival to the lab. Participants in the control group remained seated for ten minutes between measurements. Participants selected for the kinetic chain protocol were given exercises that engage musculature of the lumbopelvic-hip complex as their warm-up protocol. Participants selected for the combination protocol were given exercises that engage musculature of the upper and lower extremities as their warm-up protocol. Three measurements were recorded and averaged for analysis for both the pre-warmup and post-warmup measurements. Results and Conclusion: A within-subjects repeated measures ANOVA revealed a significant difference between the selected warm-up and right shoulder internal rotational strength (F(2,3)=24.63, p=0.014). The combination protocol resulted in a slight increase in right shoulder internal rotational strength compared to the intervention and control protocols. No other measurements of strength elicited any differences. The combination warm up protocol took the glenohumeral joint through its full range of motion, specifically targeted musculature of the upper extremity and possibly influencing the isometric strength of the internal rotators on the right side. These findings should be tested on a larger scale to determine if these results are generalizable to all active college-aged individuals