The neuromuscular, biochemical, and endocrine responses to a single-session vs. double-session training day in elite athletes

Purpose: The aim of this study was to compare the acute neuromuscular, biochemical, and endocrine responses of a training day consisting of a speed session only to performing a speed and weight training session on the same day. Methods: Fifteen male academy level rugby players completed two protocols in a randomized order. The speed only protocol involved performing 6 maximal effort repetitions of 50m running sprints with 5 minutes recovery between each sprint, while the speed and weights protocol involved the same sprinting session but was followed 2h post by a lower body weights session consisting of 4 sets of 5 back squat and Romanian deadlift at 85% 1RM. Testosterone, cortisol, creatine kinase, lactate, and perceived muscle soreness were determined immediately before, immediately after, 2h post, and 24h post both protocols. Peak power, relative peak power, jump height, and average rate of force development were determined from a counter movement jump (CMJ) at the same time points. Results: At 24h post, muscle soreness was significantly higher following the speed and weights protocol compared to speed only protocol (effect size eta2= .253, F=4.750, p < 0.05). There was no significant difference between any of the CMJ variables at any of the post training time points. Likewise creatine kinase, testosterone, and cortisol were unaffected by the addition of a weight training session. Conclusion: These data indicate that the addition of a weight training session 2h post a speed session, while increasing the perception of fatigue the following day, does not result in a difference in endocrine response or in neuromuscular capability

Neuromuscular responses to mild-muscle damaging eccentric exercise in a low glycogen state.

The aim of this study was to examine the effect of low muscle glycogen on the neuromuscular responses to maximal eccentric contractions. Fourteen healthy men (22±3years) performed single-leg cycling (20min at ∼75% maximal oxygen uptake (V̇O2 max); eight 90 s sprints at a 1:1 work-to-rest ratio (5% decrements from 90% to 55% V̇O2 max until exhaustion) the evening before 100 eccentric (1.57rads(-1)) with reduced (RED) and normal glycogen (NORM). Neuromuscular responses were measured during and up to 48h after with maximal voluntary and involuntary (twitch, 20Hz and 50Hz) isometric contractions. During eccentric contractions, peak torque decreased (RED: -16.1±2.5%; NORM: -6.2±5.1%) and EMG frequency increased according to muscle length. EMG activity decreased for RED only. After eccentric contractions, maximal isometric force was reduced up to 24h for NORM (-13.5±5.8%) and 48h for RED (-7.4±10.9%). Twelve hours after eccentric contractions, twitch force and the 20:50Hz ratio were decreased for RED but not for NORM. Immediate involuntary with prolonged voluntary force loss suggests that reduced glycogen is associated with increased susceptibility to mild muscle-damaging eccentric exercise with contributions of peripheral and central mechanisms to be different during recovery

The effect of session order on the physiological, neuromuscular, and endocrine responses to maximal speed and weight training sessions over a 24-h period

Objectives: Athletes are often required to undertake multiple training sessions on the same day with these sessions needing to be sequenced correctly to allow the athlete to maximize the responses of each session. We examined the acute effect of strength and speed training sequence on neuromuscular, endocrine, and physiological responses over 24 hours. Design: 15 academy rugby union players completed this randomized crossover study. Method: Players performed a weight traiing session followed 2 hours later by a speed training session (WS) and on a separate day reversed the order (SW). Countermovement jumps (CMJ), perceived muscle soreness (MS), and blood samples were collected immediately prior, immediately post, and 24 hours post sessions one and two respectively. Jumps were analyzed for power, jump height, rate of force development, and velocity. Blood was analyzed for testosterone (T), cortisol (C), lactate and creatine kinase (CK). Results: There were no differences between CMJ variables at any of the post training time points (p > 0.05). Likewise, CK, T, C , and MS were unaffected by session order (p > 0.05). However, 10 meter sprint time was significantly faster (Mean ± SD; SW 1.80s ± 0.11 vs. WS 1.76 ± 0.08s; p > 0.05) when speed was sequenced second. Lactate levels were significantly higher immediately post speed sessions versus weight training sessions at both time points (p < 0.05). Conclusions: The sequencing of strength and speed training does not affect the neuromuscular, endocrine, and physiological recovery over 24 hours. However, speed may be enhanced when performed as the second session

Physiological comparison between non-athletes, endurance, power and team athletes.

We hypothesized that endurance athletes have lower muscle power than power athletes due to a combination of weaker and slower muscles, while their higher endurance is attributable to better oxygen extraction, reflecting a higher muscle oxidative capacity and larger stroke volume. Endurance (n = 87; distance runners, road cyclists, paddlers, skiers), power (n = 77; sprinters, throwers, combat sport athletes, body builders), team (n = 64; basketball, soccer, volleyball) and non-athletes (n = 223) performed a countermovement jump and an incremental running test to estimate their maximal anaerobic and aerobic power (VO2max), respectively. Dynamometry and M-mode echocardiography were used to measure muscle strength and stroke volume. The VO2max (L min-1) was larger in endurance and team athletes than in power athletes and non-athletes (p < 0.05). Athletes had a larger stroke volume, left ventricular mass and left ventricular wall thickness than non-athletes (p < 0.02), but there were no significant differences between athlete groups. The higher anaerobic power in power and team athletes than in endurance athletes and non-athletes (p < 0.001) was associated with a larger force (p < 0.001), but not faster contractile properties. Endurance athletes (20.6%) had a higher (p < 0.05) aerobic:anaerobic power ratio than controls and power and team athletes (14.0-15.3%). The larger oxygen pulse, without significant differences in stroke volume, in endurance than power athletes indicates a larger oxygen extraction during exercise. Power athletes had stronger, but not faster, muscles than endurance athletes. The similar VO2max in endurance and team athletes and similar jump power in team and power athletes suggest that concurrent training does not necessarily impair power or endurance performance

Prefrontal Cortex Activity Predicts Mental Fatigue in Young and Elderly Men During a 2 h “Go/NoGo” Task

Background: Although the effects of mental fatigue on cognitive–motor function and psychological state in young adults are well-documented, its effects in the elderly are not completely understood. The aim of this study was to estimate the effect of prolonged cognitive load on the indicators of psychological, cognitive, and motor functions.Methods: Fifteen young and 15 elderly men were asked to perform a 2 h “Go/NoGo” task. Psychological state (mood and motivation), cognitive (prefrontal cortex activity and cognitive performance), and motor (motor cortex excitability and grip strength) functions were measured before and after the task. During the 2 h task, both groups had a significantly similar increase in the number of “Incorrect NoGo” errors. Only in young men reaction time (RT) of “Incorrect NoGo” and intraindividual variability of RT of “Incorrect NoGo” significantly increased during task. After the task, handgrip strength decreased for the young men, whereas latency of motor evoked potentials prolonged both groups. Nevertheless, both groups indicated that they felt fatigue after the 2 h task; we observed that mental demand increased, whereas intrinsic motivation and mood decreased only in young men. Prolonged task decreased the switching/rest ratio of oxygenated hemoglobin for the young and the elderly men; however, greater for elderly than young men. Interestingly, the more the prefrontal cortex was activated before the 2 h task during the switching task, the fewer of “Incorrect NoGo” errors made by the young men and the greater the number of errors made by the elderly men.Conclusion: Because of the greater mental load and (possibly) greater activation of prefrontal cortex during the 2 h “Go/NoGo” task, there was greater mental and neuromuscular performance fatigue in young men than in elderly men

Human alpha-actinin-3 genotype association with exercise-induced muscle damage and the repeated-bout effect

Alpha-actinin-3 (ACTN3) is an integral part of the Z line of the sarcomere. The ACTN3 R577X (rs1815739) polymorphism determines the presence or absence of functional ACTN3, which may influence the extent of exercise-induced muscle damage. This study aimed to compare the impact of, and recovery from, muscle-damaging eccentric exercise on subjects with or without functional ACTN3. Seventeen young men (20-33 years old), homozygous for the R (n = 9) or X (n = 8) alleles, performed two bouts of stretch-shortening exercise (50 drop jumps) two weeks apart. Muscle soreness, plasma creatine kinase (CK) activity, jump height, maximal voluntary isometric torque (MVC), peak concentric isokinetic torque (IT), and electrically stimulated knee extension torques at 20 and 100 Hz were measured at baseline and at a number of time points up to 14 days after each bout. There were no significant baseline differences between the groups. However, significant time point &times; genotype interactions were observed for MVC (p = 0.021) and IT (p = 0.011) for the immediate effect of eccentric exercise in bout 1. The RR group showed greater voluntary force decrements (RR vs. XX: MVC, -33.3% vs. -24.5%; IT, -35.9% vs. -23.2%) and slower recovery. A repeated-bout effect was clearly observed, but there were no differences by genotype group. The ACTN3 genotype modulates the response of muscle function to plyometric jumping exercise, although the differences are modest. The ACTN3 genotype does not influence the clearly observed repeated-bout effect; however, XX homozygotes recover baseline voluntary torque values faster and thus may be able to undertake more frequent training sessions

High-velocity elastic-band training improves hamstring muscle activation and strength in basketball players.

BACKGROUND:The aim of this study was use surface EMG activity to assess changes in co- activation of knee flexors and extensors muscle groups during elastic-band exercise after 5 weeks of high-velocity elastic-band training in basketball players. METHODS:College male basketball players (n = 18) were randomly divided into one of two groups: (1) The elastic-band training group performed low-load and high-velocity - lying prone - hamstring curls training three times per week; (2) The control group did not do any training. Pre- and post- training assessment included concentric knee extension and flexion at 60°/s and 240°/s, and the frequency of knee flexion and extension with elastic bands in the prone position. The EMG of the rectus femoris, semitendinosus muscles and the long head of the biceps femoris were assessed during these activities, and 30-m sprint running speed was measured from a stationary start and a running start. RESULTS:It was shown that high-velocity elastic-band training was 1) feasible, 2) increased movement velocity and 3) muscle strength, 4) altered neural control such that excessive lengthening of the hamstring muscle, and hence strain-injuries, may be prevented and 5) improved sprint performance in basketball players. CONCLUSIONS:In addition, these results suggest that high-velocity elastic-band training may be a tool to prevent hamstring strain-injuries in basketball players

Absence of Bilateral Differences in Child Baseball Players with Throwing-related Pain

© Georg Thieme Verlag KGStuttgart · New York.The aim of this study was to assess whether side-to-side differences in morphology and function of the upper limbs in 11-12 year-old male baseball players with throwing-related pain (n=14) were more pronounced than that of age-matched healthy untrained subjects (n=16). Baseball players 1) had played baseball≥4.5 h·wk−1 for ≥ 4 years and (2) suffered from moderate-intensity (3-6 points on 10-point questionnaire scale) throwing-related pain in the shoulder or elbow in at least 2 training sessions within the past month. The range of motion (ROM), function and structure of the elbows and shoulders were assessed using goniometry, isokinetic dynamometry and ultrasonography. While the ROM and eccentric external peak torque of internal shoulder rotation were lower, the thickness of the supraspinatus tendon, the ulnar collateral ligament and articular cartilage of the humeral head were larger in baseball players than controls. There were, however, no significant side-to-side differences in any parameter in either group. In conclusion, it is unlikely that side-to-side differences in shoulder and upper limb structure and function contributed to the throwing-related pain in young baseball players, but low shoulder eccentric external peak torque and range of internal rotation may predispose to throwing-related pain

Locomotor Muscle Fatigue Does Not Alter Oxygen Uptake Kinetics during High-Intensity Exercise

The V˙O2 slow component (V˙O2sc) that develops during high-intensity aerobic exercise is thought to be strongly associated with locomotor muscle fatigue. We sought to experimentally test this hypothesis by pre-fatiguing the locomotor muscles used during subsequent high-intensity cycling exercise. Over two separate visits, eight healthy male participants were asked to either perform a non-metabolically stressful 100 intermittent drop-jumps protocol (pre-fatigue condition) or rest for 33 min (control condition) according to a random and counterbalanced order. Locomotor muscle fatigue was quantified with 6-s maximal sprints at a fixed pedaling cadence of 90 rev·min−1. Oxygen kinetics and other responses (heart rate, capillary blood lactate concentration and rating of perceived exertion, RPE) were measured during two subsequent bouts of 6 min cycling exercise at 50% of the delta between the lactate threshold and V˙O2max determined during a preliminary incremental exercise test. All tests were performed on the same cycle ergometer. Despite significant locomotor muscle fatigue (P = 0.03), the V˙O2sc was not significantly different between the pre-fatigue (464 ± 301 mL·min−1) and the control (556 ± 223 mL·min−1) condition (P = 0.50). Blood lactate response was not significantly different between conditions (P = 0.48) but RPE was significantly higher following the pre-fatiguing exercise protocol compared with the control condition (P < 0.01) suggesting higher muscle recruitment. These results demonstrate experimentally that locomotor muscle fatigue does not significantly alter the V˙O2 kinetic response to high intensity aerobic exercise, and challenge the hypothesis that the V˙O2sc is strongly associated with locomotor muscle fatigue

Physical Activity and Healthy Habits Influence Mood Profile Clusters in a Lithuanian Population

Moods have been investigated previously in a range of cultural contexts. In our study, we investigated if six mood profiles previously identified, termed the iceberg, inverse Everest, inverse iceberg, shark fin, submerged, and surface profiles, were also evident among a Lithuanian sample. A Lithuanian translation of the Brunel Mood Scale (BRUMS-LTU) was completed by a sample of 746 participants (male = 199, female = 547) aged from 17–78 years (M = 41.8 years, SD = 11.4 year). Seeded k-means cluster analysis clearly identified the six hypothesized mood profiles, the prevalence of which reflected previous findings. Cluster prevalence varied significantly by sex, age, exercise and smoking status, frequency of overeating, and self-rated health of participants. Male participants and older adults were under-represented for the inverse Everest profile and over-represented for the iceberg profile. Those who reported more healthy habits (i.e., exerciser, non-smoker, rarely overeat) and those reporting better self-rated health were over-represented for the iceberg profile and under-represented for negative mood profiles; namely, the inverse Everest, inverse iceberg, and shark fin profiles. Findings supported the cross-cultural invariance of the mood profile clusters and confirmed the link between unhealthy habits and negative mood profile