Power-trained Athletes Research Articles

Heart rate variability and stress perception: The influence of physical fitness

The autonomic nervous system (ANS) is somewhat linked to perceived stress. This relationship may be modulated by the individual's training status. The aim was to assess whether heart rate variability (HRV) and perceived stress were interrelated in healthy subjects with various levels of training status. One hundred and seventeen healthy participants (mean age 20 ± 3 yrs) were divided into 3 groups according to their training status: power-trained athletes ( n = 43), endurance-trained athletes ( n = 36), and untrained volunteers ( n = 38). The perception of stress was measured using the perceived stress scale questionnaire, heart rate (HR) was recorded at rest, and HRV analyses were made in time and frequency domain using the Kubios application. Endurance-trained athletes showed higher levels of HRV compared to untrained and, to a lesser extent, to power athletes. HRV parameters of untrained subjects perceiving less stress did not differ from those of endurance-trained athletes who also perceived less stress. Power-trained athletes who perceived less stress had higher values of SD1, RMSSD, HF, and log HF ( P < 0.05, P < 0.05, P < 0.01; P < 0.05 respectively) compared to those who perceived more stress. Our data indicate that training status modulates HRV, and that changes in perceived stress are associated with changes in HRV. Power-trained athletes who perceived less stress had greater HRV compared to athletes who perceived more stress. These results may be important in terms of understanding ANS modulation and stress perception for better managements of stress and/or training/recovery processes in athletes with various training status. Le système nerveux autonome (SNA) est quelque peu lié à la perception du stress. Cette relation peut être modulée par le statut d’entraînement du sujet. L’objectif était d’évaluer si la variabilité de la fréquence cardiaque (VFC) et le stress perçu étaient interdépendants chez des sujets sains mais ayant différents niveaux d’aptitude physique. Cent dix-sept participants (âge moyen 20 ± 3 ans) ont été subdivisés en 3 groupes en fonction de leur statut d’entraînement : athlètes entraînés en puissance ( n = 43), athlètes entraînés en endurance ( n = 36) et des sujets non entraînés ( n = 38). Le stress perçu a été mesuré à l’aide d’une échelle de perception du stress. La fréquence cardiaque (FC) a été enregistrée au repos et les analyses de la VFC ont été effectuées à l’aide de l’application Kubios. Les athlètes entraînés en endurance ont montré des niveaux plus élevés de VFC par rapport aux sujets non entraînés et, dans une moindre mesure, aux athlètes de puissance. Les paramètres de la VFC des sujets non entraînés percevant moins de stress ne différaient pas de ceux des athlètes endurants qui percevaient également moins de stress. Les athlètes entraînés en puissance qui percevaient moins de stress avaient des valeurs plus élevées de SD1, RMSSD, HF et log HF ( p < 0,05, p < 0,05, p < 0,01; p < 0,05 respectivement) par rapport à ceux qui percevaient plus de stress. Nos données indiquent que le statut d’entraînement module la VFC et que les changements du stress perçu sont associés à des changements de la VFC. Les athlètes entraînés en puissance, qui percevaient moins de stress, avaient une plus grande VFC par rapport aux athlètes qui ressentaient plus de stress. Ces résultats peuvent être importants en termes de compréhension de la modulation du SNA et de la perception du stress pour une meilleure gestion du stress et/ou des processus d’entraînement/récupération chez des sujets ayant différents statuts d’entraînement.

High vibration frequency of soft tissue occurs during gait in power-trained athletes

ABSTRACT Muscles serve as a critical regulator of locomotion and damping, resulting in changes of soft tissue vibration. However, whether muscle fibre compositions of different individuals will cause different extents of soft tissue vibration during gait is unclear. Therefore, this study investigated the differences in lower extremity vibration frequencies among power-trained and non-power-trained athletes during walking and running. Twelve weightlifting athletes were assigned to the power-trained group and twelve recreational runners were assigned to the non-power-trained group. Accelerometers were used to detect soft tissue compartment vibration frequencies of the rectus femoris (RF) and gastrocnemius medialis (GMS) during walking and running. Results indicated that power-trained athletes, as compared to the non-power-trained, induced significantly (p < 0.05) higher vibration frequencies in their soft tissue compartments during walking and running. This suggests that power-trained athletes, who have higher ratios of fatigable fast-twitch muscle fibres, may have induced higher soft tissue compartment vibration frequencies. As a result, there is a likelihood that power-trained athletes may recruit more fatigable fast-twitch muscle fibres during muscle tuning, causing dysfunctions during prolonged exercises.

Aerobic Fitness Changes In Trained And Untrained Subjects Following A Three Week Cycling Course

The health and fitness related benefits of endurance training are numerous and well documented. As training progresses, however, the window for training-specific improvement narrows, making continued performance gains challenging. PURPOSE: The purpose of this study was to compare changes in aerobic fitness between endurance-trained athletes (ET), power-trained athletes (PT), and non-athletes (NON) before and after completing a 3 week college cycling course. It was hypothesized that improvement in aerobic fitness would be greatest for NON and least for ET. METHODS: 19 subjects (12 male, 7 female; mean age 20±0.5 yr.) enrolled in a cycling course at Alma College participated in the study. Participants were categorized into 3 groups (ET, PT, or NON) based on their sport-specific training prior to taking the course. Training for this study consisted of cycling an average of 5 days/week for 18-44 miles/day for 3 weeks, with mileage and course difficulty increasing throughout the training. Participants performed a 5-mile time trial pre- and post-training utilizing a standardized cycle trainer and road bike. Time to completion and average power (Watts) were recorded for each participant and utilized to compare fitness changes among groups. One-way ANOVAs were used to compare the change in time to completion and power pre-to-post training among groups (ET, PT, NON), and paired t-tests were used to compare pre-training to post-training. RESULTS: There was no significant difference in time to completion (p=0.81) or average power (p=0.43) on the 5-mile time trial among groups, although all groups decreased time to completion by 0.98±0.92 minutes (p<0.01) and increased average power by 13.5±20.9 Watts (p=0.01). CONCLUSIONS: An intensive, 3-week cycling training program elicited similar improvements in aerobic fitness in a sample of college students, regardless of prior training status.

Wingate Anaerobic Test Reliability on the Velotron With Ice Hockey Players.

Bringhurst, RF, Wagner, DR, and Schwartz, S. Wingate anaerobic test reliability on the velotron with ice hockey players. J Strength Cond Res 34(6): 1716-1722, 2020-This study evaluated the test-retest reliability of the Wingate Anaerobic Test (WAnT) performed on a Velotron electromagnetically braked cycle ergometer for power-trained athletes and assessed whether a familiarization trial was necessary to achieve high test-retest reliability. Twenty-one male ice hockey players (age 23.5 ± 4.7 years, mass 86.3 ± 16.6 kg, height 180.9 ± 7.4 cm) from a collegiate club team (Club = 10) and a recreational league (Rec = 11) performed three 30-second WAnTs within 2 weeks and with at least 24 hours between visits. Mean power (MP), anaerobic capacity, peak power (PP), anaerobic power, maximum revolutions per minute, and fatigue index were assessed. Resistance was 8.5% of the participant's body mass. The effect of time on power output was moderated (p < 0.001, (Equation is included in full-text article.)= 0.24) such that a significant increase was observed after a practice trial, but not between subsequent trials for the Club players; no practice effect was observed among Rec players. Extremely high reliability (ICC1,1) was found between trials after excluding the practice trial (MP = 0.973, anaerobic capacity = 0.975, PP = 0.957, and anaerobic power = 0.890). Club players achieved higher outputs despite no significant differences in body size or age compared with Rec players. Ice hockey players performing the 30-second WAnT on the Velotron electromagnetically braked cycle ergometer had highly reliable data, and using a familiarization trial is recommended to increase reliability and achieve higher power outputs.

Changes in Stress and Appetite Responses in Male Power-Trained Athletes during Intensive Training Camp.

An intensive consecutive high-volume training camp may induce appetite loss in athletes. Therefore, this study aimed to investigate the changes in stress and appetite responses in male power-trained athletes during an intensive training camp. The measurements at Day 2 and at the end of a 9-day intensive training camp (Camp1 and Camp2, respectively) were compared with those of the resting period (Rest) and the regular training period (Regular; n = 13). The stress state was assessed based on plasma cortisol level, salivary immunoglobulin A level, and a profile of mood states score. The sensation of appetite was assessed using visual analog scale scores, and fasting plasma acylated ghrelin, insulin, and glucose were measured. The cortisol concentrations were significantly higher at Camp2 (466.7 ± 60.7 nmol∙L−1) than at Rest (356.3 ± 100.9 nmol∙L−1; p = 0.002) or Regular (361.7 ± 111.4 nmol∙L−1; p = 0.003). Both prospective and actual food consumption significantly decreased at Camp2, and acylated ghrelin concentration was significantly lower at Camp1 (34.2 ± 8.0 pg∙mL−1) and Camp2 (32.0 ± 8.7 pg∙mL−1) than at Rest (47.2 ± 11.2 pg∙mL−1) or Regular (53.4 ± 12.6 pg∙mL−1). Furthermore, the change in acylated ghrelin level was negatively correlated with the change in cortisol concentration. This study’s findings suggest that an early-phase physiological stress response may decrease the acylated ghrelin level in male power-trained athletes during an intensive training camp.

Hyperventilation-induced respiratory alkalosis falls short of countering fatigue during repeated maximal isokinetic contractions.

Hyperventilation, implemented during recovery of repeated maximal sprints, has been shown to attenuate performance decrement. This study evaluated the effects of hyperventilation, using strength exercises, on muscle torque output and EMG amplitude. Fifteen power-trained athletes underwent maximal isokinetic knee extensions consisting of 12 repetitions × 8 sets at 60°/s and 25 repetitions × 8 sets at 300°/s. The inter-set interval was 40 s for both speeds. For the control condition, subjects breathed spontaneously during the interval period. For the hyperventilation condition, subjects hyperventilated for 30 s before each exercise set (50 breaths/min, PETCO2: 20-25 mmHg). EMG was recorded from the vastus medialis and lateralis muscles to calculate the mean amplitude for each contraction. Hyperventilation increased blood pH by 0.065-0.081 and lowered PCO2 by 8.3-10.3 mmHg from the control values (P < 0.001). Peak torque declined with repetition and set numbers for both speeds (P < 0.001), but the declining patterns were similar between conditions. A significant, but small enhancement in peak torque was observed with hyperventilation at 60°/s during the initial repetition phase of the first (P = 0.032) and fourth sets (P = 0.040). EMG amplitude also declined with set number (P < 0.001) for both speeds and muscles, which was, however, not attenuated by hyperventilation. Despite a minor ergogenic effect in peak torque at 60°/s, hyperventilation was not effective in attenuating the decrement in torque output at 300°/s and decrement in EMG amplitude at both speeds during repeated sets of maximal isokinetic knee extensions.

Organ Size Increases With Weight Gain in Power-Trained Athletes

The purpose of this study was to determine whether overfeeding and high-intensity physical training increase organ mass. We examined this question using cross-sectional and longitudinal studies in which we measured collegiate male American football players. Freshman (n = 10) and senior players in their second and third years of college (n = 17) participated in the cross-sectional study. The same measurements of the same freshman players (n = 10) were assessed after the one-year weight gain period in the longitudinal study. Fat-free mass (FFM), skeletal muscle, and adipose tissue mass were obtained using dual-energy X-ray absorptiometry. Liver, kidney, brain, and heart volumes were calculated using magnetic resonance imaging or echocardiography. Compared with the freshman players, the senior players had 10.8 kg more FFM, and 0.29 kg, 0.08 kg, and 0.09 kg greater liver, heart, and kidney mass, respectively. In the longitudinal study, FFM, liver, heart, and kidney mass of the freshman players increased by 5.2 kg, 0.2 kg, 0.04 kg, and 0.04 kg, respectively, after one year of overfeeding and physical training. On the other hand, the organ-tissue mass to FFM ratio did not change, except for the brain, in either the cross-sectional or longitudinal studies. Our results indicated that the organ-tissue masses increased with overfeeding and physical training in male collegiate American football players.

Relationship Between Postactivation Potentiation of Knee Extensor Muscles, Sprinting and Vertical Jumping Performance in Professional Soccer Players

Little is known about the relationship between postactivation potentiation (PAP) in human muscles, assessed by enhancement of twitch torque after a conditioning maximal voluntary contraction (MVC), and performance in activities requiring power and speed. Moreover, no studies have assessed PAP in soccer players who train power and endurance simultaneously. The purpose of the present study was to examine the relationship between twitch PAP in knee extensor (KE) muscles, and sprinting and vertical jumping performance in soccer players. Fourteen professional male soccer players with mean (SD) age 20.0 (3.6) years, height 177.9 (6.9) cm and body mass 70.5 (5.7) kg) were tested for 15-m sprint time, vertical jump height in countermovement (CMJ) and squat (SJ) jumps. PAP in KE muscles was induced by a 10-s isometric MVC. Electrically evoked twitches of KE muscles were evoked before and after the conditioning MVC. Immediately after the conditioning MVC, twitch peak torque (PT) and maximal rates of torque development and relaxation were significantly potentiated. A significant negative correlation was found between 15-m sprint time and jump height in CMJ (r = -0.63) and SJ (r = -0.57). PAP of twitch PT correlated significantly positively with jump height in CMJ (r = 0.61) and SJ (r = 0.64), and negatively with 15-m sprint time (r = -0.59). In conclusion, twitch PAP in KE muscles was significantly correlated with performance in vertical jumping and sprinting in male professional soccer players, whereas the magnitude of PAP in soccer players was similar to that observed previously in power-trained athletes.

Neuromuscular Responses to Platform Perturbations in Power-Versus Endurance-Trained Athletes

The purpose was to assess differences in postural response characteristics between two groups of elite athletes having power or endurance training. Participants were all men and included power- (M age = 21 yr., SD = 3, n = 12) and endurance-trained (M age = 22, SD = 3, n = 12) athletes. Muscle response characteristics and center of pressure measures were recorded during recovery from Fast (10 cm at 80 cm/sec.) and Slow (10 cm at 20 cm/sec.) horizontal platform perturbations. In response to Fast perturbations, power-trained athletes responded with significantly shorter times to stabilize the center of pressure, shorter muscle-contraction onset times, and larger muscle response amplitudes than endurance-trained athletes. This suggests power-trained athletes are more effective than endurance-trained athletes in responding to balance threats such as slips and trips in daily life and that power training should be studied to improve balance control of balance-impaired populations.

The use of pupillometry in the assessment of cardiac autonomic function in elite different type trained athletes

The aim of the present study was to evaluate cardiac autonomic function by pupillometry in male athletes. Fifteen elite endurance- (END) and eleven power-trained (POWER) athletes and fifteen sedentary individuals (CONTROL) were studied. All subjects underwent three pupillometric measurements: at rest, peak exercise testing and recovery phase. The pupillometric indices studied were: baseline pupil radius (R1), minimum pupil radius (R2), maximum constriction velocity (VC(max)), maximum constriction acceleration (AC(max)), amplitude (AMP, R1-R2), constriction ratio (AMP%). During exercise, RR intervals were obtained for each subject with a Polar S810i for time and frequency domain heart rate variability (HRV) analysis. The following parameters of HRV were measured: standard deviation of all NN intervals (SDNN), the mean square successive differences (rMSSD), percent of NN intervals differing >50 ms from the preceding NN (pNN50), low (LF)- and high (HF)- frequency components of the autoregressive power spectrum of the NN intervals and their ratio (LF/HF). At rest and recovery, END showed significantly increased VC(max) and AC(max) compared to POWER and CONTROL. AMP% was significantly greater in END at rest, peak exercise and recovery compared to POWER and CONTROL. END and POWER had significantly greater AMP at rest and recovery compared to CONTROL. Moreover, all HRV indices were significantly increased in END compared to POWER and CONTROL. However, POWER showed significantly increased rMSSD and LF compared to CONTROL. HRV parameters were significantly correlated with pupillometric parameters during exercise. Our results indicated that any kind of exercise training and mainly endurance one affects autonomic regulation of pupillary light reflex.

Time Course of Postactivation Potentiation During Intermittent Submaximal Fatiguing Contractions in Endurance- and Power-Trained Athletes

This study aimed to measure time course of postactivation potentiation during intermittent submaximal fatiguing isometric contractions in 2 groups of subjects with different physical training history. Fifteen men subjects (8 endurance-trained athletes [END] and 7 power-trained athletes [POW]) performed a 10-minute intermittent (5-second contraction, 5-second rest) knee extension exercise at 50% of their maximal voluntary isometric contraction. Mechanical (peak twitch torque, Pt) and electrophysiological (M-wave) responses following electrical stimulation of the femoral nerve were measured at rest and every 10 s throughout exercise. Vastus lateralis (VL) muscle activity (root mean square, RMS) was recorded during each contraction, and the RMS/M ratio was calculated. A significant increase in Pt (+52%, p < 0.01) was observed in both groups during the first minute of the exercise. Thereafter Pt decreased dramatically (p < 0.05) in POW whereas it remained above baseline values in END until the end of exercise. The VL RMS/M ratio increased from 7 minutes of exercise for the entire population of subjects, but showed a tendency toward greater and earlier increase in POW. Our study showed the effectiveness of an intermittent submaximal preconditioning protocol to induce similar potentiation (5-10 repetitions of 5-second submaximal contraction at 50% MVC of knee-extensors) for 2 groups of trained-individuals with different muscular profiles (END vs. POW). The enhanced fatigue resistance of endurance athletes allows the potentiating effect to prevail longer over the fatigue effect during all the 10-minute exercise. The proposed conditioning protocol (moderate-intensity, short-duration intermittent exercise) as an interesting alternative compared to MVC is adequate to warm all athletes and increase sports performance.

Recurrence quantification analysis of surface electromyographic signal: Sensitivity to potentiation and neuromuscular fatigue

This study aimed to assess the capacity of recurrence quantification analysis (RQA) to detect potentiation and to determine the fatigue components to which RQA is sensitive. Fifteen men were divided in two groups [8 endurance-trained athletes (END) and 7 power-trained athletes (POW)]. They performed a 10-min intermittent (5 s contraction, 5 s rest) knee extension exercise at 50% of their maximal voluntary isometric contraction. Muscular fatigue and potentiation were evaluated with neurostimulation technique. Mechanical (peak torque, Pt) and electrophysiological (M-wave) responses following electrical stimulation of the femoral nerve were measured at rest and every 10 s throughout exercise. Vastus lateralis muscle activity (root mean square, RMS) was recorded during each contraction, and RMS was normalized to M-wave area (RMS/M). During contraction, muscle activity was analyzed with RQA to obtain the percentage of determinism (%Det). At the beginning of exercise, a significant Pt increase (+52%, P < 0.001) was observed in both groups, indicating potentiation. At this time, %Det remained constant in both groups, indicating that RQA did not detect potentiation. Thereafter, Pt decreased in POW from 5 min 30 s of exercise (−30%, P < 0.001), reflecting impairment in excitation–contraction coupling, and %Det increased from 3 min 30 s ( P < 0.01). In END, Pt remained high and %Det was unchanged. These two results indicated that RQA detected the peripheral component of fatigue. Conversely, RQA did not detect central adaptation to fatigue since %Det remained constant when a significant increase in RMS/M ( P < 0.01) appeared in END.

Determinants of difference in leg stiffness between endurance- and power-trained athletes

Understanding the leg and joint stiffness during human movement would provide important information that could be utilized for evaluating sports performance and for injury prevention. In the present study, we examined the determinants of the difference in the leg stiffness between the endurance-trained and power-trained athletes. Seven distance runners and seven power-trained athletes performed in-place hopping, matching metronome beats at 3.0 and 1.5 Hz. Leg and joint stiffness were calculated from kinetic and kinematics data. Electromyographic activity (EMG) was recorded from six leg muscles. At both hopping frequencies, the power-trained athletes demonstrated significantly higher leg stiffness than the distance runners. Hip, knee, and ankle joints were analyzed for stiffness and touchdown angles. Ankle stiffness was significantly greater in the power-trained athletes than the distance runners at 3.0 Hz as was knee stiffness at 1.5 Hz. There was no significant difference in touchdown angle between the DR and PT groups at either hopping frequencies. When significant difference in EMG activity existed between two groups, it was always greater in the distance runners than the power-trained athletes. These results suggest that (1) the difference in leg stiffness between endurance-trained and power-trained athletes is best attributed to increased joint stiffness, and (2) the difference in joint stiffness between the two groups may be attributed to a lack of similarity in the intrinsic stiffness of the muscle-tendon complex rather than in altered neural activity.

Effects of High-Intensity Isokinetic Exercise on Salivary Cortisol in Athletes with Different Training Schedules: Relationships to Serum Cortisol and Lactate

Physical exercise is associated with increases of serum and salivary levels of cortisol. The concomitant increase in serum lactate has been implicated as one of the mechanisms responsible for adrenocortical activation. We evaluated the responses of serum lactate and serum and salivary cortisol to an acute bout of high-intensity isokinetic exercise in eleven non-competitive and twenty competitive athletes (NCA and CA, respectively). The latter group was composed of endurance- and power-trained athletes (EA and PA, respectively). Aims of the study were to determine interindividual differences in the lactate and cortisol responses as a function of type and intensity of training and to search for relationships both between lactate and cortisol production and between serum and salivary cortisol levels. The isokinetic exercise test elicited significant cortisol and lactate responses. No difference was evident in the lactate responses between NCA and CA, while the PA showed a higher response during and after the exercise in comparison to EA (peak levels immediately after the exercise: PA 15.0 +/- 1.5 mmol/l vs. EA 11.1 +/- 2.6 mmol/l, p < 0.01). Serum cortisol was higher in the CA in comparison to the NCA group at 30 and 120 minutes after the termination of the exercise, while no differential response was evident between EA and PA groups. Salivary cortisol response was higher in the CA group in comparison to NCA immediately after the exercise and at 90 and 120 minutes after the termination and was higher in PA in comparison to EA at 60, 90, and 120 minutes after the termination (peak levels at 60 minutes: PA 51.2 +/- 18.5 nmol/l vs. EA 27.5 +/- 20.8 nmol/l, p < 0.05). No significant correlations were found between serum or salivary cortisol and lactate levels. The relationship between serum and salivary cortisol was markedly non-linear, the slope of the serum-saliva regression line being lower for serum cortisol concentrations over 500 nmol/l than for concentrations below that value (0.019 and 0.037, respectively, p < 0.01). We have confirmed in this particular setting the existence of an important adrenocortical response that can be reliably and non invasively assessed by a serial saliva sampling and have supported the concept that cortisol and lactate responses to a high-intensity isokinetic exercise are independent. The interindividual differences in cortisol changes are likely to be related to the training status and mode as well as to the correspondence between the evaluation protocol and the discipline individually performed.

HOFFMANN REFLEX DOES NOT DIFFER BETWEEN ENDURANCE TRAINED, POWER TRAINED AND CONTROLS

The Hoffmann reflex (H-reflex) has been suggested to differ among athletes depending upon their type of training. Power trained athletes are suggested to have lower Hmax/Mmax ratios when compared to non-trained controls or endurance trained athletes. Additionally, endurance trained athletes are suggested to have greater Hmax/Mmax ratios compared to non-trained controls. PURPOSE To compare the Hoffmann reflex as measured by the maximal H-reflex to M-response ratio of male Division I endurance trained athletes (ET), power trained athletes (PT), and non-trained control subjects (NT). METHODS ET was composed of 19 cross-country athletes, 20 sprinters were in PT, and 29 normally active college age males in NT. Aerobic power (treadmill), anaerobic power (Wingate Anaerobic Test), body composition (hydrostatic weighing), maximal soleus H-reflex, and maximal soleus M-response were measured. Measurements for ET and PT occurred at the beginning of the cross-country season and indoor track season respectively. Values are reported as the mean ± SEM. One-way Anova and Tukey HSD were used to determine group differences. RESULTS ET had significantly higher aerobic power compared to PT and NT (67.4 ± 1.1 ml·kg−1· min−1 vs. 52.4 ± 1.2 and 50.2 ± 1.0, respectively). Mean anaerobic power was significantly lower in ET than PT and NT (453.7 ± 13.9 Watts vs. 566.4 ± 25.8 and 562.8 ± 15.3, respectively). Percent body fat was significantly lower in ET and PT than NT (7.9 ± 0.7 % and 7.8 ± 0.9 vs. 13.3 ± 0.9, respectively). Soleus Hmax/Mmax ratio was not different between any of the groups (ET; 0.569 ± 0.037, PT; 0.545 ± 0.065, and NT; 0.590 ± 0.027). CONCLUSION Contrary to previous reports, H-relex did not differ between athletes training for endurance events and athletes training for power events. Further, athletes did not differ from non-trained controls in soleus motoneuron pool excitability. Two possible reasons our results differ from previous reports may be 1) our larger sample size or 2) the difference in time during the training season when measurements were made.

Effects of Training on the Exercise-Induced Changes in Serum Amino Acids and Hormones

The purpose of this study was to examine power-type athletes to determine changes in amino acid and hormone concentrations in circulating blood following 2 different high-intensity exercise sessions before and after the 5-week training period. Eleven competitive male sprinters and jumpers performed 2 different running exercise sessions: a short run session (SRS) of 3 × 4 × 60 m (intensity of 91–95%) with recoveries of 120 and 360 seconds, and a long run session (LRS) with 20-second intervals (intensity of 56–100%) with recoveries of 100 seconds to exhaustion. The concentrations of serum amino acids, hormones, and lactate were determined from the blood samples drawn after an overnight fast and 10 minutes before and after both SRS and LRS. The average blood lactate concentrations were 12.7 ± 1.6 mmol·L-1 and 16.6 ±1.4 mmol·L-1 (p < 0.01) following SRS and LRS, respectively. The average total running time was longer (p < 0.001) following LRS (164 ± 20 seconds) than following SRS (91 ± 8 seconds). The fasting levels of all amino acids decreased (p = 0.024; 19.4%) after the 5-week period, whereas an increase (p = 0.007; 24.5%) was observed in the fasting concentration of testosterone (TE). The exercise sessions induced no changes in the total sum of all amino acids, but significant increases or decreases were observed in single amino acids. When the range of the relative concentration changes before and after the training period was compared, significant decreases were found in valine (p = 0.048), asparagine (p = 0.029), and taurine (p = 0.030) following SRS. There were significant increases in the absolute hormonal concentration changes following LRS with TE (p = 0.002; 30.4%), cortisol (COR; p = 0.006; 12.0%), and in the TE/COR ratio (p = 0.047; 21.0%) but not in the concentration of growth hormone (GH). The results of the study indicate that the speed and strength training period strongly decreases the fasting concentrations of amino acids in the power-trained athletes in a good anabolic state with the daily protein intake of 1.26 g·kg-1 body weight. At the same time the intensive lactic exercise session induces strong decreases, especially in valine, asparagine, and taurine.

Effects of Training on the Exercise-Induced Changes in Serum Amino Acids and Hormones

The purpose of this study was to examine power-type athletes to determine changes in amino acid and hormone concentrations in circulating blood following 2 different high-intensity exercise sessions before and after the 5-week training period. Eleven competitive male sprinters and jumpers performed 2 different running exercise sessions: a short run session (SRS) of 3 x 4 x 60 m (intensity of 91-95%) with recoveries of 120 and 360 seconds, and a long run session (LRS) with 20-second intervals (intensity of 56-100%) with recoveries of 100 seconds to exhaustion. The concentrations of serum amino acids, hormones, and lactate were determined from the blood samples drawn after an overnight fast and 10 minutes before and after both SRS and LRS. The average blood lactate concentrations were 12.7 +/- 1.6 mmol;pdL(-1) and 16.6 +/- 1.4 mmol;pdL(-1) (p < 0.01) following SRS and LRS, respectively. The average total running time was longer (p < 0.001) following LRS (164 +/- 20 seconds) than following SRS (91 +/- 8 seconds). The fasting levels of all amino acids decreased (p = 0.024; 19.4%) after the 5-week period, whereas an increase (p = 0.007; 24.5%) was observed in the fasting concentration of testosterone (TE). The exercise sessions induced no changes in the total sum of all amino acids, but significant increases or decreases were observed in single amino acids. When the range of the relative concentration changes before and after the training period was compared, significant decreases were found in valine (p = 0.048), asparagine (p = 0.029), and taurine (p = 0.030) following SRS. There were significant increases in the absolute hormonal concentration changes following LRS with TE (p = 0.002; 30.4%), cortisol (COR; p = 0.006; 12.0%), and in the TE/COR ratio (p = 0.047; 21.0%) but not in the concentration of growth hormone (GH). The results of the study indicate that the speed and strength training period strongly decreases the fasting concentrations of amino acids in the power-trained athletes in a good anabolic state with the daily protein intake of 1.26 g;pdkg(-1) body weight. At the same time the intensive lactic exercise session induces strong decreases, especially in valine, asparagine, and taurine.

The Load That Maximizes the Average Mechanical Power Output During Explosive Bench Press Throws in Highly Trained Athletes

The power output generated with different barbell loads and which resistance generated the maximum mechanical power output (Pmax) during explosive bench press-type throws (BT) in a smith machine device were investigated in power-trained athletes. Thirty-one rugby league players were tested for 1 repetition maximum (1RM) free-weight bench press strength (1RM BP). Maximal power output was assessed by the Plyometric Power System during BT using resistances of 40, 50, 60, 70, and 80 kg (BT P40, BT P50, BT P60, BT P70, and BT P80). It was found that BT Pmax occurred with resistance of 70.1 ± 7.9 kg, representing 55 ± 5.3% of 1RM BP of 129.7 ± 14.3 kg. The power output with all loads except the BT P70 were different from the BT Pmax. The BT P70 and BT P80 were not different from each other. Furthermore, the BT P60 and BT P80 were not different from each other. This suggests that although resistances of 55% 1RM BP may maximize power output during explosive BT, loads in the range of 46–62% also allow for high power outputs. Resistances of 31–45% of 1RM BP resulted in significantly lower power outputs. Compared with previous research of BT in strength-trained athletes, the results of this investigation suggest that power-trained athletes may generate their Pmax at higher percentages of 1RM.

The Load That Maximizes the Average Mechanical Power Output During Jump Squats in Power-Trained Athletes

Three studies that used rugby league players experienced in power training methods as subjects were performed to investigate the resistance (percentage of 1 repetition maximum [1RM]) that maximized the average mechanical power output (Pmax) during the jump squat exercise. Maximum strength was assessed via 1RM (studies 2 and 3) or 3RM (study 1) during the full-squat exercise. Pmax was assessed during barbell jump squats, using resistances of 40, 60, 80, and 100 kg within the Plyometric Power System. All studies found that power output was maximized by resistances averaging circa 85–95 kg, representing 55–59% of 1RM full-squat strength. However, loads in the range of 47–63% of 1RM were often similarly effective in maximizing power output. The results of this investigation suggest that athletes specifically trained via both maximal strength and power training methods may generate their maximal power outputs at higher percentages of 1RM than those previously reported for solely strength-trained athletes and that there would appear to be an effective range of resistances for maximizing power output.

The Load That Maximizes the Average Mechanical Power Output During Explosive Bench Press Throws in Highly Trained Athletes

The power output generated with different barbell loads and which resistance generated the maximum mechanical power output (Pmax) during explosive bench press-type throws (BT) in a smith machine device were investigated in power-trained athletes. Thirty-one rugby league players were tested for 1 repetition maximum (1RM) free-weight bench press strength (1RM BP). Maximal power output was assessed by the Plyometric Power System during BT using resistances of 40, 50, 60, 70, and 80 kg (BT P40, BT P50, BT P60, BT P70, and BT P80). It was found that BT Pmax occurred with resistance of 70.1 +/- 7.9 kg, representing 55 +/- 5.3% of 1RM BP of 129.7 +/- 14.3 kg. The power output with all loads except the BT P70 were different from the BT Pmax. The BT P70 and BT P80 were not different from each other. Furthermore, the BT P60 and BT P80 were not different from each other. This suggests that although resistances of 55% 1RM BP may maximize power output during explosive BT, loads in the range of 46-62% also allow for high power outputs. Resistances of 31-45% of 1RM BP resulted in significantly lower power outputs. Compared with previous research of BT in strength-trained athletes, the results of this investigation suggest that power-trained athletes may generate their Pmax at higher percentages of 1RM.