ß-Hydroxy-ß-methylbutyrate free acid reduces markers of exercise-induced muscle damage and improves recovery in resistance-trained men.

The purpose of the present study was to determine the effects of short-term supplementation with the free acid form of b-hydroxyb-methylbutyrate (HMB-FA) on indices of muscle damage, protein breakdown, recovery and hormone status following a high-volume resistance training session in trained athletes. A total of twenty resistance-trained males were recruited to participate in a high-volume resistance training session centred on full squats, bench presses and dead lifts. Subjects were randomly assigned to receive either 3 g/d of HMB-FA or a placebo. Immediately before the exercise session and 48 h post-exercise, serum creatine kinase (CK), urinary 3-methylhistadine (3-MH), testosterone, cortisol and perceived recovery status (PRS) scale measurements were taken. The results showed that CK increased to a greater extent in the placebo (329%) than in the HMB-FA group (104%) (P»0·004, d » 1·6). There was also a significant change for PRS, which decreased to a greater extent in the placebo (9·1 (SEM 0·4) to 4·6 (SEM 0·5)) than in the HMB-FA group (9·1 (SEM 0·3) to 6·3 (SEM 0·3)) (P»0·005, d » 20·48). Muscle protein breakdown, measured by 3-MH analysis, numerically decreased with HMB-FA supplementation and approached significance (P»0·08, d » 0·12). There were no acute changes in plasma total or free testosterone, cortisol or C-reactive protein. In conclusion, these results suggest that an HMB-FA supplement given to trained athletes before exercise can blunt increases in muscle damage and prevent declines in perceived readiness to train following a high-volume, muscle-damaging resistance-training session.

Changes in perceived recovery status scale following high-volume muscle damaging resistance exercise.

Currently no research has investigated the relationship between muscle damage, hormonal status, and perceived recovery scale (PRS). Therefore, the purpose of this study was to determine the effects of a high-volume training session on PRS and to determine the relationship between levels of testosterone, cortisol, and creatine kinase (CK) and PRS. Thirty-five trained subjects (21.3 ± 1.9 years) were recruited. All subjects participated in a high-volume resistance training session consisting of 3 sets of full squats, bench press, deadlifts, pullups, dips, bent over rows, shoulder press, and barbell curls and extensions. Pre-PRS and post-PRS measurements (0-10), soreness, CK, cortisol, and testosterone were measured before and 48 hours after training. Perceived recovery scale declined from 8.6 ± 2.3 to 4.2 ± 1.85 (p < 0.05). Leg, chest, and arm soreness increased from pre- to postexercise. Creatine kinase significantly increased from pre- to postworkout (189.4 ± 100.2 to 512 ± 222.7 U/L). Cortisol, testosterone, and free testosterone did not change. There was an inverse relationship between CK and PRS (r = 0.58, p < 0.05). When muscle damage was low before training, cortisol and free and total testosterone were not correlated to PRS. However, when damage peaked at 48 hours postexercise, free, but not total, testosterone showed a low direct relationship with PRS (r = 0.2, p < 0.05). High-volume resistance exercise lowers PRS scores. These changes are partly explained by a rise in serum indices of muscle damage. Moreover, free testosterone seems to have a positive relationship with PRS.

The effects of potentiating stimuli intensity under varying rest periods on vertical jump performance and power.

Previous research has demonstrated that post-activation potentiation (PAP) increases in an intensity-dependent manner. However, these studies did not control for volume loads. The purpose of this study was to investigate the effects of varying intensities and rest period lengths, while controlling for volume load, on vertical jump (VJ) performance. Thirteen men, aged 21 ± 3 years with an average relative full squat of 1.7 ± 2 times their body weight, were recruited for this study. Participants were assigned to 3 different experimental sessions that required them to perform the back squat at 56% (low intensity), 70% (moderate intensity), and 93% (high intensity) of their 1 repetition maximums. Vertical jump height and power were recorded at 0, 2, 4, 8, and 12 minutes after squat. There was a significant condition by time interaction for VJ height and power, in which both variables did not change in the low-intensity condition, whereas decreasing immediately after squat for both the moderate- and high-intensity conditions. In the moderate- and high-intensity conditions, VJ height and power increased and peaked at minute 4 and returned to baseline by minutes 8 and 12. These results indicate that when controlling for total work, jump performance and power are enhanced similarly by moderate and high squat intensities. However, high-intensity workloads may prolong the duration of PAP. Therefore, athletes may use moderate- and high-intensity loads during warm-ups to improve jump performance and power.

Pescadillo interacts with the cadmium response element of the human heme oxygenase-1 promoter in renal epithelial cells.

Renal tubular cells elicit adaptive responses following exposure to nephrotoxins, such as cadmium. One response is the up-regulation of the 32-kDa redox-sensitive protein, heme oxygenase-1. Exposure of renal proximal tubular epithelial cells to 10 mum cadmium demonstrated induction ( approximately 20-fold) of heme oxygenase-1 mRNA and protein. Using a 4.5-kb human heme oxygenase-1 promoter construct, the importance of a previously identified cadmium response element (TGCTAGAT) in HeLa cells was verified in renal epithelial cells. Specific protein-DNA interaction with this sequence was demonstrated using nuclear extracts from cadmium-treated cells. Yeast one-hybrid screen of a human kidney cDNA library resulted in the identification of pescadillo, a unique nucleolar, developmental protein, as an interacting protein with the cadmium response element and was confirmed by chromatin immunoprecipitation in vivo and gel shift assays with purified glutathione S-transferase-pescadillo protein in vitro. The specificity of the DNA-protein interaction was verified by the absence of a binding complex when the core sequence of the cadmium response element was mutated or deleted. In addition, B23/nucleophosmin, another nucleolar protein, did not interact with the cadmium response sequence. Overexpression of pescadillo resulted in increased activity of the 4.5-kb human heme oxygenase-1 promoter construct but failed to activate this construct when the cadmium response sequence was mutated. The findings demonstrate the important and previously unrecognized role of pescadillo as a DNA-binding protein interacting specifically with the cadmium response element of the human heme oxygenase-1 gene.

The story so far: Molecular regulation of the heme oxygenase-1 gene in renal injury.

Heme oxygenases (HOs) catalyze the rate-limiting step in heme degradation, resulting in the formation of iron, carbon monoxide, and biliverdin, the latter of which is subsequently converted to bilirubin by biliverdin reductase. Recent attention has focused on the biological effects of product(s) of this enzymatic reaction, which have important antioxidant, anti-inflammatory, and cytoprotective functions. Two major isoforms of the HO enzyme have been described: an inducible isoform, HO-1, and a constitutively expressed isoform, HO-2. A third isoform, HO-3, closely related to HO-2, has also been described. Several stimuli implicated in the pathogenesis of renal injury, such as heme, nitric oxide, growth factors, angiotensin II, cytokines, and nephrotoxins, induce HO-1. Induction of HO-1 occurs as an adaptive and beneficial response to these stimuli, as demonstrated by studies in renal and non-renal disease states. This review will focus on the molecular regulation of the HO-1 gene in renal injury and will highlight the interspecies differences, predominantly between the rodent and human HO-1 genes.