Relationship Between Endogenous Creatine Levels and Maximal Upper Body Strength, Short Term Muscle Recovery and Body Fat In Males

Numerous studies have found creatine supplementation to positively enhance performance but no research found has examined the effects of endogenous creatine levels on performance. The purpose of this study was twofold. First we examined correlations between endogenous creatine levels and strength, absolute strength, short term muscle recovery and body fat. We also examined the effects of creatine supplementation with a sufficient washout period on plasma creatinine levels. Participants consisted of 24 healthy men who met with the experimenter twice over a 4 day period. Significant positive correlations (p .05) were found between creatine and strength, absolute strength, lean body mass and muscle recovery as a function of total weight lifted following 3 and 5 sets of the muscle fatigue protocol

THE EFFECTS OF AGING ON MYOSTATIN PATHWAY ACTIVITY AFTER THREE SEQUENTIAL BOUTS OF RESISTANCE EXERCISE

Background. Myostatin signaling serves to regulate skeletal muscle mass by influencing genes responsible for regulating satellite cell activity and by participating in glucocorticoid induced skeletal muscle atrophy; however research investigating myostatin pathway signaling is still in its infancy.Purpose. The purpose of this investigation was two-fold: 1) To examine if baseline differences in myostatin signaling exist between younger (18-35 yr) and older (65-80 yr) men. 2) To examine if short-term, chronic resistance training can ameliorate potential differences in myostatin signaling that exist between younger and older adults.Methods. Younger (n = 10; age: 21.0 ± 0.5 years, body mass: 82.3 ± 4.2 kg, height: 178.4 ± 2.2 cm, body fat percentage: 15.4 ± 2.9%) and older (n = 10; age: 66.4 ± 1.6 years, body mass: 94.2 ± 3.7 kg, height: 180.9 ± 2.2 cm, body fat percentage: 27.4 ± 1.8%) men chose to participate in the current investigation. Participants were one repetition maximum tested (1 RM) for leg press, hack squat and leg extension. Then participants underwent two familiarization sessions separated by 48 hours before partaking in three training sessions separated by 48 hours which consisted of 3 sets of 10 repetitions at 80% of 1RM for each of the previously mentioned exercises. Percutaneous muscle biopsies were collected from the vastus lateralis prior to the exercise intervention (T1), 48 hours following workout 1 (T2), 48 hours following workout 2 (T3), and 24 hours following workout 3 (T4). The mRNA expression of MYOSTATIN, ACTIVIN IIB, HSGT, TITIN CAP, FLRG, FOLLISTATIN and SMURF1 were analyzed in duplicate and expressed using the 2-&#8710;CT method where &#8710;CT = (gene of interest - the average of B2M and 28S). The protein expression of phosphorylated Smad3 (pSmad3) was determined using western blotting procedures.Results. Younger men had a significantly greater 1 RM for hack squat (younger: 170.0 ± 10.9 kg, older: 105.8 ± 10.4 kg; p = 0.001), leg press (younger: 271.1 ± 14.6 kg, older: 182.7 ± 14.9 kg; p < 0.001) and leg extension (younger: 64.8 ± 4.0 kg, older: 46.7 ± 2.8 kg; p = 0.002) compared to older men. As a result the cumulative training volume was significantly greater during the training bouts in younger compared to older men (younger: 36,392 ± 1,894 kg, older: 23,724 ± 1,639 kg; p < 0.001). Three day food diaries indicated that relative caloric (young = 33.4 ± 5.1 kcal/kg/d, old = 19.5 ± 1.9 kcal/kg/d; p = 0.038), protein (young = 1.6 ± 0.2 g/kg/d, old = 0.8 ± 0.1 g/kg/d; p = 0.030), carbohydrate (young = 4.1 ± 0.6 g/kg/d, old = 2.3 ± 0.3 g/kg/d; p = 0.017) and fat (young = 1.2 ± 0.2 g/kg/d, old = 0.6 ± 0.1 g/kg/d; p = 0.006) consumption were each significantly greater in younger compared to older men. Non-parametric statistics were used for the assessment of mRNA and protein data. The only between groups differences for the mRNA expression of the genes of interest occurred at baseline (p = 0.038) and T4 (p = 0.005) for FLRG and baseline (p = 0.023) and T2 (p = 0.008) for FOLLISTATIN in which older men had significantly greater mRNA expression values compared to younger men. The only significant within group changes occurred in the mRNA expression of MYOSTATIN as older men had a significant downregulation following T3 (p = 0.047) and T4 (p = 0.013), while younger men experienced a trend decrease following T4 (p = 0.074). Significant between group differences were present in the protein expression of pSmad3 following T3 (p = 0.012) and T4 (p = 0.010).Conclusions. Baseline differences in myostatin signaling were present as older men had significantly greater mRNA levels of the myostatin binding proteins FLRG and FOLLISTATIN compared to younger men. The myostatin pathway signaling response following short-term, chronic resistance training was similar between younger and older men. However, alterations in myostatin pathway signaling following repeated resistance training bouts was more favorable in older men. Specifically, older men experienced a significant decrease in the mRNA expression of MYOSTATIN at T3 and T4. Older men also had significantly lower pSmad protein levels at T3 and T4 compared to younger men. Decrements in serum androgen concentrations appear to be primarily responsible for the loss of skeletal muscle mass with age. However, in attempt to maintain skeletal muscle mass with age positive physiological adaptations have been found to occur such as an increase in the mRNA expression of ANDROGEN RECEPTOR and myogenic regulatory factors. Results from the current investigation provide evidence that favorable adaptations occur in myostatin pathway signaling to promote skeletal muscle growth with age and following short-term, chronic resistance training

A higher effort-based paradigm in physical activity and exercise for public health: making the case for a greater emphasis on resistance training

It is well known that physical activity and exercise is associated with a lower risk of a range of morbidities and all-cause mortality. Further, it appears that risk reductions are greater when physical activity and/or exercise is performed at a higher intensity of effort. Why this may be the case is perhaps explained by the accumulating evidence linking physical fitness and performance outcomes (e.g. cardiorespiratory fitness, strength, and muscle mass) also to morbidity and mortality risk. Current guidelines about the performance of moderate/vigorous physical activity using aerobic exercise modes focuses upon the accumulation of a minimum volume of physical activity and/or exercise, and have thus far produced disappointing outcomes. As such there has been increased interest in the use of higher effort physical activity and exercise as being potentially more efficacious. Though there is currently debate as to the effectiveness of public health prescription based around higher effort physical activity and exercise, most discussion around this has focused upon modes considered to be traditionally ‘aerobic’ (e.g. running, cycling, rowing, swimming etc.). A mode customarily performed to a relatively high intensity of effort that we believe has been overlooked is resistance training. Current guidelines do include recommendations to engage in ‘muscle strengthening activities’ though there has been very little emphasis upon these modes in either research or public health effort. As such the purpose of this debate article is to discuss the emerging higher effort paradigm in physical activity and exercise for public health and to make a case for why there should be a greater emphasis placed upon resistance training as a mode in this paradigm shift

The Relationship Between Endogenous Creatine Levels and Maximal Upper Body Strength, Short Term Muscle Recovery and Body Fat in Males

Author\u27s abstract: Numerous studies have found creatine supplementation to positively enhance performance but no research found has examined the effects of endogenous creatine levels on performance. The purpose of this study was twofold. First we examined correlations between endogenous creatine levels and strength, absolute strength, short term muscle recovery and body fat. We also examined the effects of creatine supplementation with a sufficient washout period on plasma creatinine levels. Participants consisted of 24 healthy men who met with the experimenter twice over a 4 day period. Significant positive correlations (p .05) were found between creatine and strength, absolute strength, lean body mass and muscle recovery as a function of total weight lifted following 3 and 5 sets of the muscle fatigue protocol

The physiological and activity demands experienced by Australian female basketball players during competition

Design: A between-subjects (positional comparison) repeated measures (playing periods) observational experimental design was followed. Methods: State-level basketball players (n = 12; age: 22.0 ± 3.7 yr; body mass: 72.9 ± 14.2 kg; stature: 174.2 ± 6.9 cm; body fat: 17.2 ± 5.6%; estimated VO2max: 43.3 ± 5.7 ml/kg/min) volunteered to participate. Heart rate (HR) and blood lactate concentration ([BLa]) were collected across eight competitive matches. Overall and positional player activity demands were calculated across three matches using time–motion analysis methodology. Activity frequencies, total durations and total distances were determined for various activity categories. Results: Mean (±SD) HR responses of 162 ± 3 b/min (82.4 ± 1.3% HRmax) and 136 ± 6 b/min (68.6 ± 3.1% HRmax) were evident across live and total time during matches. A mean [BLa] of 3.7± 1.4 mmol/L was observed across competition. Player activity demands were unchanged across match periods, with 1752 ± 186 movements performed and 5214 ± 315 m travelled across total live match time. Furthermore, 39 ± 3%, 52 ± 2%, 5 ± 1% and 4 ± 1% of total live time was spent performing low-intensity, moderate-intensity, high-intensity and dribbling activity. Positional comparisons revealed backcourt players performed more ball dribbling (p < 0.001) and less standing/walking (p < 0.01) and running (p < 0.05) than frontcourt players. Conclusions: Together, these findings highlight the high intermittent demands and important contributions of both anaerobic and aerobic metabolic pathways during state-level female basketball competition

Gender-specific activity demands experienced during semi-professional basketball game-play

Purpose: To compare game activity demands between female and male semi-professional basketball players. Methods: Female (n = 12) and male (n = 12) semi-professional basketball players were monitored across three competitive games. Time-motion analysis procedures quantified player activity into pre-defined movement categories across backcourt (BC) and frontcourt (FC) positions. Activity frequencies, durations, and distances were calculated relative to live playing time (∙min-1). Work:rest ratios were also calculated using the video data. Game activity was compared between genders for each playing position and all players. Results: Female players performed at greater running work-rates than males (45.7 ± 1.4 vs. 42.1 ± 1.7 m∙min-1, P = 0.05), while male players performed more dribbling than females (2.5 ± 0.3 vs. 3.0 ± 0.2 s∙min-1; 8.4 ± 0.3 vs. 9.7 ± 0.7 m∙min-1, P = 0.05). Positional analyses revealed female BC players performed more low-intensity shuffling (P = 0.04) and jumping (P = 0.05), as well as longer (P = 0.04) jogging durations than male BC players. Female FC players executed more upper-body activity (P = 0.03) and larger work:rest ratios (P < 0.001) than male FC players. No significant gender differences were observed in the overall intermittent demands, distance traveled, high-intensity shuffling activity, and sprinting requirements during game-play. Conclusions: These findings highlight that gender-specific running and dribbling differences might exist in semi-professional basketball. Further, position-specific variations between female and male basketball players should be considered. These data may prove useful in the development of gender-specific conditioning plans relative to playing position in basketball

Moderate-intensity running causes intervertebral disc compression in young adults

BACKGROUND: Decreased intervertebral disc (IVD) volume can result in diminished load carrying capacity of the spinal region. Although moderate intensity running is generally advocated for apparently healthy adults, running causes a loss in stature that is thought to reflect IVD compression. The aim of this investigation was to use magnetic resonance imaging (MRI) to quantify the influence of moderate-intensity treadmill running on IVD height and volume in the thoracic and lumbar regions of the vertebral column. METHODS: A clinic-based repeated measures design was used in eight healthy young asymptomatic adults. After preliminary measurements and familiarization (day 1), participants reported to the clinic on two further occasions. MRI scans and stature measurements were completed at baseline (day 2), preexercise (day 3), and after 30 min of moderate-intensity treadmill running (postexercise; day 3). Mean height and volume were derived for all thoracic and lumbar IVDs from digitized MRIs and stature was determined with a stadiometer. RESULTS: Moderate intensity running resulted in 6.3 ± 0.9% reduction in mean IVD height and 6.9 ± 1.0% reduction in calculated IVD volume. The day-to-day variation in mean IVD height and volume were 0.6 ± 0.6% and 0.4 ± 0.6%, respectively. CONCLUSION: This is the first study to quantify the influence of moderate-intensity running on IVD height and volume. Changes in IVD height and volume were observed throughout the thoracic and lumbar vertebral regions. These findings suggest that future studies evaluating the influence of various loading activities and recovery techniques on IVD structure should consider thoracic as well as lumbar regions of the spine

The intra-match activity variation during elite and sub-elite open-age Australian male basketball competitions

This study described the variation in activity demands experienced across match quarters in open-age Australian male basketball competition and compare these changes between elite and sub-elite playing levels. The results suggest that elite basketball players experience greater reductions in HIA towards the end of matches compared with sub-elite players. These differences may have been due to greater fatigue responses and tactical strategies reducing the pace of match activity towards the end of elite competition. In contrast, increased stoppage durations and more effective pacing strategies across sub-elite competition may have permitted improved maintenance of high-intensity activity across match quarters within these players