Postexercise muscle cooling enhances gene expression of PGC-1α

This study aimed to investigate the influence of localized muscle cooling on postexercise vascular, metabolic, and mitochondrial-related gene expression.

Development of a valid and reliable video-based decision-making test for Australian football umpires

To develop a valid and reliable video-based decision-making test to examine and monitor the decision-making performance of Australian football umpires.

Associations of overall sitting time and TV viewing time with fibrinogen and C reactive protein: the AusDiab study.

Sedentary behaviour is associated with increased risk for all-cause and cardiovascular mortality. Plasma fibrinogen and C reactive protein (CRP)-key inflammatory and/or haemostatic markers-may contribute to this association; however, few studies have examined their relationships with sedentary behaviours. We examined associations of overall sitting and TV viewing time with fibrinogen and high-sensitivity CRP (hsCRP).

Muscle atrophy, pain, and damage in bed rest reduced by resistive (vibration) exercise

The purpose of this study was to investigate the effectiveness of a short-duration (5-6 min, 3 d·wk) resistive exercise program with (RVE) or without (RE) whole-body vibration in reducing muscle atrophy in the lower limb during prolonged inactivity when compared with that in an inactive control group. METHODS: As part of the second Berlin BedRest Study, 24 male subjects underwent 60 d of head-down tilt bed rest. Using magnetic resonance imaging, muscle volumes of the individual muscles of the lower limb were calculated before and at various intervals during and after bed rest. Pain levels and markers of muscle damage were also evaluated during and after bed rest. Adjustment of P values to guard against false positives was performed via the false discovery rate method. RESULTS: On the "intent-to-treat" analysis, RE reduced atrophy of the medial and lateral gastrocnemius, soleus, vasti, tibialis posterior, flexor hallucis longus, and flexor digitorum longus (P ≤ 0.045 vs control group) and RVE reduced atrophy of the medial and lateral gastrocnemius and tibialis posterior (P ≤ 0.044). Pain intensity reports after bed rest were lower in RE at the foot (P ≤ 0.033) and whole lower limb (P = 0.01) and in RVE at the thigh (P ≤ 0.041), lower leg (P ≤ 0.01), and whole lower limb (P ≤ 0.036). Increases in sarcomere-specific creatine kinase after bed rest were less in RE (P = 0.020) and RVE (P = 0.020). No differences between RE and RVE were observed. CONCLUSIONS: In conclusion, a short-duration RVE or RE can be effective in reducing the effect of prolonged bed rest on lower extremity muscle volume loss during bed rest and muscle damage and pain after bed rest. Copyright © 2014 by the American College of Sports Medicine.

Ibuprofen treatment blunts early translational signaling responses in human skeletal muscle following resistance exercise.

Cyclooxygenase-1 and -2 pathway-derived prostaglandins (PGs) have been implicated in adaptive muscle responses to exercise, but the role of PGs in contraction-induced muscle signaling has not been determined. We investigated the effect of inhibition of cyclooxygenase-1 and -2 activities with the nonsteroidal anti-inflammatory drug ibuprofen on human muscle signaling responses to resistance exercise. Subjects orally ingested 1,200 mg ibuprofen (or placebo control) in three 400-mg doses administered ∼30 min before and ∼6 h and ∼12 h following a bout of unaccustomed resistance exercise (80% one repetition maximum). Muscle biopsies were obtained at rest (preexercise), immediately postexercise (0 h), 3 h postexercise, and at 24 h of recovery. In the placebo (PLA) group, phosphorylation of ERK1/2 (Thr202/Tyr204), ribosomal protein S6 kinase (RSK, Ser380), mitogen-activated kinase 1 (Mnk1, Thr197/202), and p70S6 kinase (p70S6K, Thr421/Ser424) increased at both 0 and 3 h postexercise, with delayed elevation of phospho (p)-p70S6K (Thr389) and p-rpS6 (Ser235/S36 and Ser240/244) at 3 h postexercise. Only p-ERK1/2 (Thr202/Tyr204) remained significantly elevated in the 24-h postexercise biopsy. Ibuprofen treatment prevented sustained elevation of MEK-ERK signaling at 3 h (p-ERK1/2, p-RSK, p-Mnk1, p-p70S6K Thr421/Ser424) and 24 h (p-ERK1/2) postexercise, and this was associated with suppressed phosphorylation of ribosomal protein S6 (Ser235/236 and Ser240/244). Early contraction-induced p-Akt (Ser473) and p-p70S6K (Thr389) were not influenced by ibuprofen, but p-p70S6K (Thr389) remained elevated 24 h postexercise only in those receiving ibuprofen treatment. Early muscle signaling responses to resistance exercise are, in part, ibuprofen sensitive, suggesting that PGs are important signaling molecules during early postexercise recovery.

Soy protein ingestion results in less prolonged p70S6 kinase phosphorylation compared to whey protein after resistance exercise in older men

BACKGROUND: The phosphorylation of p70S6 Kinase (p70S6K) is an important step in the initiation of protein translation. p70S6K phosphorylation is enhanced with graded intakes of whey protein after resistance exercise. Soy protein ingestion results in lower muscle protein synthesis after exercise compared with whey; however, the underlying mechanisms responsible for this difference have not been reported. FINDINGS: 13 older men (60-75) completed an acute bout of lower body resistance exercise and ingested 30 g of soy protein or carbohydrate. Muscle biopsies were obtained in the rested and fasted state and 2 and 4 hours post exercise. Phosphorylation status of p70S6K was measured with western blot. Results were compared with previously reported data from the ingestion of 30 g of whey protein or placebo. p70S6K phosphorylation was increased 2, but not 4 hours post exercise with soy protein ingestion. p70S6K phosphorylation was not increased post exercise with carbohydrate ingestion. CONCLUSIONS: Ingesting 30 g of either whey or soy protein resulted in equivalent p70S6K phosphorylation at 2 hours post exercise, however, unlike whey, soy protein failed to promote prolonged phosphorylation of p70S6K to 4 hours post-exercise.

Game and training load differences in elite junior Australian football

Game demands and training practices within team sports such as Australian football (AF) have changed considerably over recent decades, including the requirement of coaching staff to effectively control, manipulate and monitor training and competition loads. The purpose of this investigation was to assess the differences in external and internal physical load measures between game and training in elite junior AF. Twenty five male, adolescent players (mean ±SD: age 17.6 ± 0.5 y) recruited from three elite under 18 AF clubs participated. Global positioning system (GPS), heart rate (HR) and rating of perceived exertion (RPE) data were obtained from 32 game files during four games, and 84 training files during 19 training sessions. Matched-pairs statistics along with Cohen's d effect size and percent difference were used to compare game and training events. Players were exposed to a higher physical load in the game environment, for both external (GPS) and internal (HR, Session-RPE) load parameters, compared to in-season training. Session time (d = 1.23; percent difference = 31.4% (95% confidence intervals = 17.4 - 45.4)), total distance (3.5; 63.5% (17.4 - 45.4)), distance per minute (1.93; 33.0% (25.8 - 40.1)), high speed distance (2.24; 77.3% (60.3 - 94.2)), number of sprints (0.94; 43.6% (18.9 - 68.6)), mean HR (1.83; 14.3% (10.5 - 18.1)), minutes spent above 80% of predicted HRmax (2.65; 103.7% (89.9 - 117.6)) and Session-RPE (1.22; 48.1% (22.1 - 74.1)) were all higher in competition compared to training. While training should not be expected to fully replicate competition, the observed differences suggest that monitoring of physical load in both environments is warranted to allow comparisons and evaluate whether training objectives are being met. Key pointsPhysical loads, including intensity, are typically lower in training compared to competition in junior elite Australian football.Monitoring of player loads in team sports should include both internal and external measures.Selected training drills should look to replicate game intensities, however training is unlikely to match the overall physical demands of competition.

Facilitating effects of transcranial direct current stimulation on motor imagery brain-computer interface with robotic feedback for stroke rehabilitation

OBJECTIVE: To investigate the efficacy and effects of transcranial direct current stimulation (tDCS) on motor imagery brain-computer interface (MI-BCI) with robotic feedback for stroke rehabilitation. DESIGN: A sham-controlled, randomized controlled trial. SETTING: Patients recruited through a hospital stroke rehabilitation program. PARTICIPANTS: Subjects (N=19) who incurred a stroke 0.8 to 4.3 years prior, with moderate to severe upper extremity functional impairment, and passed BCI screening. INTERVENTIONS: Ten sessions of 20 minutes of tDCS or sham before 1 hour of MI-BCI with robotic feedback upper limb stroke rehabilitation for 2 weeks. Each rehabilitation session comprised 8 minutes of evaluation and 1 hour of therapy. MAIN OUTCOME MEASURES: Upper extremity Fugl-Meyer Motor Assessment (FMMA) scores measured end-intervention at week 2 and follow-up at week 4, online BCI accuracies from the evaluation part, and laterality coefficients of the electroencephalogram (EEG) from the therapy part of the 10 rehabilitation sessions. RESULTS: FMMA score improved in both groups at week 4, but no intergroup differences were found at any time points. Online accuracies of the evaluation part from the tDCS group were significantly higher than those from the sham group. The EEG laterality coefficients from the therapy part of the tDCS group were significantly higher than those of the sham group. CONCLUSIONS: The results suggest a role for tDCS in facilitating motor imagery in stroke.

Modulating exercise-induced hormesis: does less equal more?

Hormesis encompasses the notion that low levels of stress stimulate or upregulate existing cellular and molecular pathways that improve the capacity of cells and organisms to withstand greater stress. This notion underlies much of what we know about how exercise conditions the body and induces long-term adaptations. During exercise, the body is exposed to various forms of stress, including thermal, metabolic, hypoxic, oxidative, and mechanical stress. These stressors activate biochemical messengers, which in turn activate various signaling pathways that regulate gene expression and adaptive responses. Historically, antioxidant supplements, nonsteroidal anti-inflammatory drugs, and cryotherapy have been favored to attenuate or counteract exercise-induced oxidative stress and inflammation. However, reactive oxygen species and inflammatory mediators are key signaling molecules in muscle, and such strategies may mitigate adaptations to exercise. Conversely, withholding dietary carbohydrate and restricting muscle blood flow during exercise may augment adaptations to exercise. In this review article, we combine, integrate, and apply knowledge about the fundamental mechanisms of exercise adaptation. We also critically evaluate the rationale for using interventions that target these mechanisms under the overarching concept of hormesis. There is currently insufficient evidence to establish whether these treatments exert dose-dependent effects on muscle adaptation. However, there appears to be some dissociation between the biochemical/molecular effects and functional/performance outcomes of some of these treatments. Although several of these treatments influence common kinases, transcription factors, and proteins, it remains to be determined if these interventions complement or negate each other, and whether such effects are strong enough to influence adaptations to exercise.

Profiling the training practices and performance of elite rowers

To investigate changes in physiology, performance, and training practices of elite Australian rowers over 6 months.

Analysis of phasic and tonic electromyographic signal characteristics: electromyographic synthesis and comparison of novel morphological and linear-envelope approaches

The pattern of tonic and phasic components in an EMG signal reflects the underlying behaviour of the central nervous system (CNS) in controlling the musculature. One avenue for gaining a better understanding of this behaviour is to seek a quantitative characterisation of these phasic and tonic components. We propose that these signal characteristics can range between unvarying, tonic and intermittent, phasic activation through a continuum of EMG amplitude modulation. In this paper, we present two new algorithms for quantifying amplitude modulation: a linear-envelope approach, and a mathematical morphology approach. In addition we present an algorithm for synthesising EMG signals with known amplitude modulation. The efficacy of the synthesis algorithm is demonstrated using real EMG data. We present an evaluation and comparison of the two algorithms for quantifying amplitude modulation based on synthetic data generated by the proposed synthesis algorithm. The results demonstrate that the EMG synthesis parameters represent 91.9% and 96.2% of the variance of linear-envelopes extracted from lumbo-pelvic muscle EMG signals collected from subjects performing a repetitive-movement task. This depended, however, on the muscle and movement-speed considered (F=4.02, p<0.001). Coefficients of determination between input and output amplitude modulation variables were used to quantify the accuracy of the linear-envelope and morphological signal processing algorithms. The linear-envelope algorithm exhibited higher coefficients of determination than the most accurate morphological approach (and hence greater accuracy, T=8.16, p<0.001). Similarly, the standard deviation of the coefficients of determination was 1.691 times smaller (p<0.001). This signal processing algorithm represents a novel tool for the quantification of amplitude modulation in continuous EMG signals and can be used in the study of CNS motor control of the musculature in repetitive-movement tasks.

Resistive exercise versus resistive vibration exercise to counteract vascular adaptations to bed rest

Bed rest results in marked vascular adaptations, and resistive vibration exercise (RVE) has been shown to be an effective countermeasure. As vibration exercise has practical and logistical limitations, the use of resistive exercise (RES) alone has the preference under specific circumstances. However, it is unknown if RES is sufficient to prevent vascular adaptations to bed rest. Therefore, the purpose of the present study was to examine the impact of RES and RVE on the vascular function and structure of the superficial femoral artery in young men exposed to 60 days of bed rest. Eighteen healthy men (age: 31 +/- 8 yr) were assigned to bed rest and randomly allocated to control, RES, or RVE groups. Exercise was applied 3 times/wk for 5-7 min/session. Resting diameter, blood flow, flow-mediated dilation (FMD), and dilator capacity of the superficial femoral artery were measured using echo-Doppler ultrasound. Bed rest decreased superficial femoral artery diameter and dilator capacity (P < 0.001), which were significantly attenuated in the RVE group (P < 0.01 and P < 0.05, respectively) but not in the RES group (P = 0.202 and P = 0.696, respectively). Bed rest significantly increased FMD (P < 0.001), an effect that was abolished by RVE (P < 0.005) but not RES (P = 0.078). Resting and hyperemic blood flow did not change in any of the groups. Thus, RVE abolished the marked increase in FMD and decrease in baseline diameter and dilator capacity normally associated with prolonged bed rest. However, the stimulus provided by RES alone was insufficient to counteract the vascular adaptations to bed rest.

Bed rest and cognition: effects on executive functioning and reaction time

INTRODUCTION: Executive functions are high-order aspects of cognition heavily dependent upon the prefrontal cortex. Both prefrontal cortex activity and executive function task performance are enhanced by participation in aerobic physical activity, suggesting that a lack of such activity during the bed rest model of prolonged weightlessness might induce executive function deficits. METHODS: Twenty-four healthy males (ages 21-45 yr) undertook 60 d of head-down bed rest (-6 degrees) for the 2nd Berlin Bed Rest Study (BBR2-2). Three executive function tasks (Iowa Gambling Task, working memory, and flanker) and a reaction time task were administered before, during, and after bed rest. RESULTS: Iowa Gambling Task scores were significantly worse during bed rest (1.7 +/- 6.9) than in other sessions (24.3 +/- 7.8). Effects on working memory and flanker task performance were less obvious, requiring practice effects to be considered. Reaction time was significantly slower after bed rest (569 +/- 42 ms) than in earlier tests (529 +/- 45 ms). There was also significantly less intrasubject variability in reaction time after bed rest, consistent with more efficient executive functioning at this stage. DISCUSSION: Our results provide some evidence for a detrimental effect of bed rest on executive functioning. Whether this stems from a lack of aerobic physical activity and/or changes in the prefrontal cortex remains to be determined. Cognitive effects of bed rest could have implications for the planned human exploration of Mars, and for medical and lifestyle conditions with inadequate levels of aerobic physical activity.

Differential atrophy of the lower-limb musculature during prolonged bed-rest

Patients with medical, orthopaedic and surgical conditions are often assigned to bed-rest and/or immobilised in orthopaedic devices. Although such conditions lead to muscle atrophy, no studies have yet considered differential atrophy of the lower-limb musculature during inactivity to enable the development of rehabilitative exercise programmes. Bed-rest is a model used to simulate the effects of spaceflight and physical inactivity. Ten male subjects underwent 56-days of bed-rest. Magnetic resonance imaging of the lower-limbs was performed at 2-weekly intervals during bed-rest. Volume of individual muscles of the lower-limb and subsequently, rates of atrophy were calculated. Rates of atrophy differed (F = 7.4, p < 0.0001) between the muscles with the greatest rates of atrophy seen in the medial gastrocnemius, soleus and vastii (p < 0.00000002). The hamstring muscles were also affected (p < 0.00015). Atrophy was less in the ankle dorsiflexors and anteromedial hip muscles (p > 0.081). Differential rates of atrophy were seen in synergistic muscles (e.g. adductor magnus > adductor longus, p = 0.009; medial gastrocnemius > lateral gastrocnemius, p = 0.002; vastii > rectus femoris, p = 0.0002). These results demonstrate that muscle imbalances can occur after extended periods of reduced postural muscle activity, potentially hampering recovery on return to full upright body position. Such deconditioned patients should be prescribed "closed-chain" simulated resistance exercises, which target the lower-limb antigravity extensor muscles which were most affected in bed-rest.

Effect of prolonged bed rest on the anterior hip muscles

Prolonged bed rest and inactivity is known to cause muscular atrophy with previous research indicating that muscles involved in joint stabilisation are more susceptible. The anterior hip muscles are important for hip joint function and stability but little is known about the effects of prolonged inactivity on their function. This study investigated the effect of prolonged bed rest on the size of the anterior hip muscles and their pattern of recovery. The effect of resistive vibration exercise (RVE) as a countermeasure to muscle atrophy was also investigated. 12 male participants, randomly assigned to either a control or an exercise group, underwent 8 weeks of bed rest with 6 months follow-up. Changes in muscle cross-sectional area (CSA) of the iliacus, psoas, iliopsoas, sartorius and rectus femoris muscles were measured by magnetic resonance imaging at regular intervals during bed rest and recovery phases. CSAs of iliopsoas and sartorius decreased at the hip joint (p<0.05) during bed rest but iliacus, psoas, and rectus femoris CSAs were unchanged (p>0.05). No significant difference was found between the two groups for all muscles (all p>0.1), suggesting inefficacy of the countermeasure in this sample. These findings suggest that prolonged bed rest can result in the atrophy of specific muscles across the hip joint which may affect its stability and function.