Matthew J. Barnes

Effect of New Zealand blueberry consumption on recovery from eccentric exercise-induced muscle damage.

BackgroundExercise-induced muscle damage (EIMD) is accompanied by localized oxidative stress / inflammation which, in the short-term at least, is associated with impaired muscular performance. Dietary antioxidants have been shown to reduce excessive oxidative stress; however, their effectiveness in facilitating recovery following EIMD is not clear. Blueberries demonstrate antioxidant and anti-inflammatory properties. In this study we examine the effect of New Zealand blueberries on EIMD after strenuous eccentric exercise.MethodsIn a randomized cross-over design, 10 females consumed a blueberry smoothie or placebo of a similar antioxidant capacity 5 and 10 hours prior to and then immediately, 12 and 36 hours after EIMD induced by 300 strenuous eccentric contractions of the quadriceps. Absolute peak and average peak torque across the knee, during concentric, isometric, and eccentric actions were measured. Blood biomarkers of oxidative stress, antioxidant capacity, and inflammation were assessed at 12, 36 and 60 hours post exercise. Data were analyzed using a two-way ANOVA.ResultsA significant (p < 0.001) decrease in isometric, concentric and eccentric torque was observed 12 hours following exercise in both treatment groups. During the 60 hour recovery period, a significant (p = 0.047) interaction effect was seen for peak isometric tension suggesting a faster rate of recovery in the blueberry intervention group. A similar trend was observed for concentric and eccentric strength. An increase in oxidative stress and inflammatory biomarkers was also observed in both treatment groups following EIMD. Although a faster rate of decrease in oxidative stress was observed in the blueberry group, it was not significant (p < 0.05) until 36 hours post-exercise and interestingly coincided with a gradual increase in plasma antioxidant capacity, whereas biomarkers for inflammation were still elevated after 60 hours recovery.ConclusionsThis study demonstrates that the ingestion of a blueberry smoothie prior to and after EIMD accelerates recovery of muscle peak isometric strength. This effect, although independent of the beverage’s inherent antioxidant capacity, appears to involve an up-regulation of adaptive processes, i.e. endogenous antioxidant processes, activated by the combined actions of the eccentric exercise and blueberry consumption. These findings may benefit the sporting community who should consider dietary interventions that specifically target health and performance adaptation.

Acute alcohol consumption aggravates the decline in muscle performance following strenuous eccentric exercise.

This study investigated the effects of acute moderate alcohol intake on muscular performance during recovery from eccentric exercise-induced muscle damage. Eleven healthy males performed 300 maximal eccentric contractions of the quadriceps muscles of one leg on an isokinetic dynamometer. They then consumed a beverage containing 1g/kg bodyweight ethanol (as vodka and orange juice) (ALC). On another occasion they performed an equivalent bout of eccentric exercise on the contralateral leg after which they consumed an isocaloric quantity of orange juice (OJ). Measurement of maximal isokinetic (concentric and eccentric) and isometric torque produced across the knee, plasma creatine kinase (CK) concentrations and muscle soreness were made before and at 36 and 60h following each exercise bout. All measures of muscle performance were significantly reduced at 36 and 60h post-exercise compared to pre-exercise measures (all p<0.05). The greatest decreases in peak strength were observed at 36h with losses of 12%, 28% and 19% occurring for OJ isometric, concentric, and eccentric contractions, respectively. However, peak strength loss was significantly greater in ALC with the same performance measures decreasing by 34%, 40% and 34%, respectively. Post-exercise plasma creatine kinase activity and ratings of muscle soreness were not different between conditions (both p>0.05). These results indicate that consumption of even moderate amounts of alcohol following eccentric-based exercise magnifies the normally observed losses in dynamic and static strength. Therefore, to minimise exercise related losses in muscle function and expedite recovery, participants in sports involving eccentric muscle work should avoid alcohol-containing beverages in the post-event period.

Does intermittent pneumatic leg compression enhance muscle recovery after strenuous eccentric exercise

Intermittent pneumatic compression (IPC) has gained rapid popularity as a post-exercise recovery modality. Despite its widespread use and anecdotal claims for enhancing muscle recovery there is no scientific evidence to support its use. 10 healthy, active males performed a strenuous bout of eccentric exercise (3 sets of 100 repetitions) followed by IPC treatment or control performed immediately after exercise and at 24 and 48 h post-exercise. Muscular performance measurements were taken prior to exercise and 24, 48 and 72 h post-exercise and included single-leg vertical jump (VJ) and peak and average isometric [knee angle 75º] (ISO), concentric (CON) and eccentric (ECC) contractions performed at slow (30° · s⁻¹) and fast (180° · s⁻¹) velocities. Plasma creatine kinase (CK) samples were taken at pre- and post-exercise 24, 48 and 72 h. Strenuous eccentric exercise resulted in a significant decrease in peak ISO, peak and average CON (30° · s⁻¹) at 24 h compared to pre-exercise for both IPC and control, however VJ performance remained unchanged. There were no significant differences between conditions (IPC and control) or condition-time interactions for any of the contraction types (ISO, CON, ECC) or velocities (CON, ECC 30° · s⁻¹ and 180° · s⁻¹). However, CK was significantly elevated at 24 h compared to pre-exercise in both conditions (IPC and control). IPC did not attenuate muscle force loss following a bout of strenuous eccentric exercise in comparison to a control. While IPC has been used in the clinical setting to treat pathologic conditions, the parameters used to treat muscle damage following strenuous exercise in healthy participants are likely to be very different than those used to treat pathologic conditions.

Comparison study of treadmill versus arm ergometry

The Bruce treadmill test is used worldwide to assess cardiovascular disease. However, because of the high increments of intensity between the stages of this test, it is not best suited to a number of populations. Therefore, the aim of the study was to determine the difference between physiological outcomes of the arm crank test and Bruce treadmill test and to provide a regression equation to account for this. Thirty subjects (16 men and 14 women) performed both an arm crank test and the Bruce treadmill test, on two separate days, in a random order. Peak values of oxygen uptake (VO2), respiratory exchange ratio (RER), ventilation rate (VE), heart rate (HR) and ratings of perceived exertion (RPE) were recorded. Arm crank VO2peak and peak VE were significantly lower compared with treadmill VO2peak and peak VE, in both men and women (P<0·001). Arm crank HRpeak was significantly lower than treadmill HRpeak in men (P<0·001). The following is the regression equation to estimate treadmill: VO2peak = 0·8*arm crank VO2peak + 0·019*body weight + 2·025*gender−0·038*gender*body weight + 0·852, with gender being ‘0’ for males and ‘1’ for females. This model has a r2 of 0·832 (SEE = 0·471). This strong correlation indicates that an accurate prediction of treadmill VO2peak can be made by arm crank VO2peak, which is a good estimate of a person’s maximal oxygen uptake (VO2max). Therefore, the arm crank test can be of great importance for evaluation of cardiovascular disease in many people.

Effects and Mechanisms of Tapering in Maximizing Muscular Strength

ABSTRACT TAPERING FOR MAXIMAL STRENGTH REQUIRES REDUCTIONS IN TRAINING LOAD TO RECOVER FROM THE FATIGUE OF TRAINING. IT IS PERFORMED BEFORE IMPORTANT COMPETITIONS TO ALLOW OPTIMAL PERFORMANCE AT SPECIFIC EVENTS. REDUCTIONS IN TRAINING VOLUME, WITH MAINTAINED OR SMALL INCREASES IN TRAINING INTENSITY, SEEM MOST EFFECTIVE FOR IMPROVING MUSCULAR STRENGTH. TRAINING CESSATION MAY ALSO PLAY A ROLE, WITH LESS THAN 1 WEEK BEING OPTIMAL FOR PERFORMANCE MAINTENANCE, AND 2–4 DAYS APPEARING TO BE OPTIMAL FOR ENHANCED MAXIMAL MUSCULAR STRENGTH. IMPROVED PERFORMANCE MAY BE RELATED TO MORE COMPLETE MUSCLE RECOVERY, GREATER NEURAL ACTIVATION, AND AN ENHANCED ANABOLIC ENVIRONMENT.

The effects of acute alcohol consumption on recovery from a simulated rugby match.

Abstract In this study, we investigated the effects of acute post-exercise alcohol consumption on measures of physical performance, creatine kinase, and immunoendocrine function in the 48 h following a rugby game simulation. Ten male senior rugby union players completed a rugby game simulation after which they consumed either 1 g of alcohol per kilogram of body mass or a non-alcoholic control beverage. Agility, 15 m sprint, countermovement jump, and srummaging performance were assessed pre-simulation and 24 and 48 h post-simulation. White blood cell count, testosterone, cortisol, and creatine kinase were measured before the simulation and 30 min, 12, 24, 36, and 48 h after the simulation. One week after the first trial, participants completed the second simulation after which the other beverage was consumed. The acute consumption of alcohol after a rugby game simulation negatively affected countermovement jump performance in the days following the simulation (P = 0.028). No differences between treatments were observed for the other criterion measures made in this study. In conclusion, after 80 min of a simulated rugby game, the consumption of 1 g of alcohol per kg body mass negatively impacts lower body vertical power output. However, performance of tasks requiring repeated maximal muscular effort is not affected.

Peak cardiac power output in healthy, trained men

Previous investigations into peak cardiac power output (CPO peak) have been limited to clinical populations and healthy, but non‐athletic adults, and normative data on trained individuals would allow a greater understanding of this parameter. Therefore, we recruited eight healthy, well‐trained male cyclists. Peak oxygen consumption ( peak) was assessed using an incremental ergometer test, and following a 40‐min recovery period, peak cardiac output (T peak) was measured during a constant load test that elicited peak (±5%) using the Defares CO2 rebreathing technique. CPO peak was calculated as described by Cooke et al. (1998) . Mean (±SD) values during the constant load test were: peak, 4·94 ± 0·41 l min−1; T peak, 36·5 ± 3·7 l min−1; mean arterial pressure, 123 ± 8 mmHg and CPO peak, 9·9 ± 1·0 W. These results demonstrate CPO peak in a well‐trained population to be approximately twice those observed in healthy, but non‐athletic adults. The current data provide useful information regarding the upper limits and possible ‘trainability’ of cardiac pumping capacity for sedentary and clinically compromised individuals.

Hemodynamic response to upright resistance exercise: effect of load and repetition.

INTRODUCTION/PURPOSE Upright resistance exercise causes large transient fluctuations in blood pressure during and immediately after the performance. We examined the effect of resistance load and the number of repetitions on the middle cerebral artery blood flow velocity (MCAv) response during and after upright squatting exercise. METHODS Healthy males (n = 12; mean ± SD: 26 ± 5 yr) completed 30%, 60%, and 90% of their six-repetition maximum load, completing two and six repetitions of these loads during two visits (order randomized). Beat-to-beat MCAv, blood pressure, and continuous end-tidal PCO2 during exercise, at nadir, and during recovery are reported as the change from preexercise standing baseline. RESULTS During exercise, MCAvmean increased 31% ± 16% (P < 0.001) across all loads (P = 0.74) and repetitions (P = 0.89), whereas mean arterial pressure (MAP) increased (all P < 0.05) as load and repetitions increased (e.g., 122 ± 9 (two repetitions) vs 135 ± 11 mm Hg (six repetitions) and 128 ± 13 vs 143 ± 14 mm Hg, at 30% and 60%, respectively). Within the six-repetition sets, peak MCAvmean remained unchanged across the set (P = 0.61), whereas MAP increased (P = 0.003). The 90% load produced the lowest MCAvmean nadir (pooled means, -18 ± 6 vs -10 ± 7 cm·s, P < 0.001 vs 30%) and MAP nadir (-34 ± 7 and -43 ± 5 mm Hg, for two and six repetitions, respectively; P < 0.001) after exercise. Postexercise MCAvmean reductions occurred via a selective, load-dependent (P < 0.001) decrease in diastolic MCAv. MCAvmean remained below baseline for the longest period after the 90% six-repetition set (10 s postexercise, P < 0.01) and took the longest to recover (14.8 ± 6.9 s, P = 0.002). CONCLUSION These data indicate that higher relative loads produce a greater postexercise hypotension and result in a proportionate reduction in MCAvmean.

Tapering practices of New Zealand's elite raw powerlifters

Abstract Pritchard, HJ, Tod, DA, Barnes, MJ, Keogh, JW, and McGuigan, MR. Tapering practices of New Zealands elite raw powerlifters. J Strength Cond Res 30(7): 1796–1804, 2016—The major aim of this study was to determine tapering strategies of elite powerlifters. Eleven New Zealand powerlifters (28.4 ± 7.0 years, best Wilks score of 431.9 ± 43.9 points) classified as elite were interviewed, using semistructured interviews, about their tapering strategies. Interviews were transcribed verbatim and content analyzed. Total training volume peaked 5.2 ± 1.7 weeks from competition while average training intensity (of 1 repetition maximum) peaked 1.9 ± 0.8 weeks from competition. During tapering, volume was reduced by 58.9 ± 8.4% while intensity was maintained (or slightly reduced) and the final weight training session was performed 3.7 ± 1.6 days out from competition. Participants generally stated that tapering was performed to achieve full recovery; that accessory work was removed around 2 weeks out from competition; and deadlifting takes longer to recover from than other lifts. Typically participants stated that trial and error, and changes based on “feel” were the sources of tapering strategies; equipment used and movements performed during tapering are the same as in competition; nutrition was manipulated during the taper (for weight cutting or performance aims); and poor tapering occurred when too long (1 week or more) was taken off training. These results suggest that athletes may benefit from continuing to strength train before important events with reduced volume and maintained intensity. Only exercises that directly assist sports performance should remain in the strength program during tapering, to assist with reductions in fatigue while maintaining/improving strength expression and performance.

Effects of hypoxia and hypercapnia on human HRV and respiratory sinus arrhythmia

PURPOSE Hypercapnia increases minute ventilation (V’E) with little effect on heart rate (HR), whereas hypoxia may increase HR without affecting V’E. However, the effects of hypercapnia and hypoxia on both heart rate variability(HRV) and the clustering of heart beats during spontaneous breathing (respiratory sinus arrhythmia – RSA), are not clear. METHODS In this study, 10 human volunteers breathed room air (RA), hypercapnic (5% CO2) or hypoxic (10%O2) gas mixtures, each for 6 min, while resting supine. ECG, mean arterial pressure (MAP), ventilatory flow, inhaled and exhaled fractions of CO2 and O2, were recorded throughout. RESULTS Both V’E and MAP increased with 5%CO2, with no change in HR. Hypoxia did not change ventilation but increased HR. High frequency components of HRV, and the relative proportion of heart beats occurring during inhalation increased with 5% CO2, but neither changed with 10% O2. CONCLUSION Increased RSA concomitant with increased MAP suggests RSA – vagal dissociation with hypercapnia. Elevated heart rate with acute hypoxia with no change in either frequency components of HRV or the distribution of heart beats during ventilation, suggested that clustering of heart beats may not be a mechanism to improve ventilation-perfusion matching during hypoxia.