Well-trained Subjects Research Articles

Detrended fluctuation analysis to determine physiologic thresholds, investigation and evidence from incremental cycling test.

Training zones are generally assessed by gas-exchange thresholds (GET). Several mathematical analyses of heart rate variability (HRV) are proposed for indirect GET determination. Our study aimed to investigate the accordance of the detrend fluctuation analysis (DFA α1) for determining GET with first (VT1) and second ventilatory (VT2) thresholds in well-trained subjects. Eighteen female and 38 male sub-elite cyclists performed a maximal incremental cycling test of 2-min stage duration with continuous gas exchange and HR measurements. Power output (PO), Oxygen uptake ( O2) and HR at VT1 and VT2 were compared with DFA α1 0.75 (HRVT1) and 0.50 (HRVT2). Agreements between PO, O2 and HR values were analyzed using Bland-Altman analysis. Large limits of agreement between VT1 and HRVT1 were observed for measures of O2 expressed in mL.min-1.kg-1 [-21.3; + 14.1], HR [39.2; + 26.9] bpm and PO [-118; + 83] watts. Indeed, agreements were also low between VT2 and HRVT2 for measures of O2 [-26.7; + 4.3] mL.min-1.kg-1, HR [-45.5; + 10.6] bpm and PO [-157; + 35] watts. Our results also showed a sex effect: women obtained worst predictions based on DFA α1 than men for HR (p = 0.014), PO (p = 0.044) at VT1 and (p = 0.045), HR (p = 0.003) and PO (p = 0.004) at VT2. There was unsatisfactory agreement between the GET and DFA α1 methods for VT1 and VT2 determination in both sex well-trained cyclists. Trial registrationnumber 2233534 on 2024/03/05 retrospectively registered.

A limited cerebellar contribution to suprasecond timing across differing task demands.

The involvement of the cerebellum in suprasecond interval timing (i.e., timing in the seconds to minutes range) is controversial. A limited amount of evidence from humans, nonhuman primates, and rodents has shown that the lateral cerebellum, including the lateral cerebellar nucleus (LCN), may be necessary for successful suprasecond timing performance. However, many existing studies have pitfalls, such as limited timing outcome measures and confounded task demands. In addition, many existing studies relied on well-trained subjects. This approach may be a drawback, as the cerebellum is hypothesized to carry out ongoing error correction to limit timing variability. By using only experienced subjects, past timing studies may have missed a critical window of cerebellar involvement. In the experiments described here, we pharmacologically inactivated the rat LCN across three different peak interval timing tasks. We structured our tasks to address past confounds, collect timing variability measures, and characterize performance during target duration acquisition. Across these various tasks, we did not find strong support for cerebellar involvement in suprasecond interval timing. Our findings support the existing distinction of the cerebellum as a subsecond interval timing brain region. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Effects Of Low Muscle Glycogen On High-intensity Exercise Performance: A Placebo-controlled Study

Muscle glycogen is the major fuel during high-intensity exercise (HIE) and large reductions can occur after relatively short durations; however, the relationship between low muscle glycogen and HIE performance has not been investigated in a placebo-controlled design. PURPOSE: To investigate the effects of low muscle glycogen content on repeated sprint ability (RSA), ratings of perceived exertion (RPE) during HIE and neuromuscular function using a double-blinded design. METHODS: Eighteen well-trained subjects (VO2max; 57 ± 5 mL·kg-1·min-1) performed glycogen-depleting cycling exercise consisting of three periods of 10x45 s at ~110% VO2max interspersed by 135 s of passive recovery between bouts and 15 min between periods. After the glycogen-depleting exercise subjects were randomly assigned to a low (LOW) or high (HIGH) carbohydrate dietary intake for 5 hours (n = 9 in each group). The diets consisted of fluid and small amounts of bars and was blinded to assessors and participants. At baseline, after each period and following the diet manipulation RSA (5x6 s sprints separated by 24 s of rest) was evaluated. Moreover, isometric knee-extensor function (maximal voluntary contractions, voluntary activation level and electrically induced low- (20 Hz) and high-frequency (50 Hz) force production) was assessed at baseline, after the exercise intervention and following the diet administration. At the same time points a 2-min fixed intensity (~90% VO2max) cycling protocol was performed with subsequent RPE measures. Finally, muscle biopsies and blood samples were obtained. RESULTS: The glycogen-depleting exercise followed by recovery in LOW and HIGH resulted in distinct glycogen concentrations (176 ± 99 vs. 292 ± 78 mmol·kg-1 dw, P < 0.01), but indifferent blood glucose concentrations (P > 0.05). This was accompanied by an impaired RSA only in LOW (7.8 ± 5.9% reduction relative to baseline, P < 0.05) coupled with a high rating of perceived exertion during HIE in LOW compared to HIGH (7.7 ± 1.2 vs. 5.6 ± 1.2 AU, P < 0.01). In contrast, no between-group difference was observed for any aspects of neuromuscular function (P > 0.05). CONCLUSIONS: Low muscle glycogen results in impaired RSA and increased RPE during HIE, whereas voluntary and electrically induced isometric knee-extensor force remains unaffected.

Safety of Bifidobacterium breve, Bif195, employing a human exercise-induced intestinal permeability model: a randomised, double-blinded, placebo-controlled, parallel group trial.

We have previously shown that the probiotic Bifidobacterium breve strain Bif195 alleviates mucosal injury including ulcer formation in the upper intestine induced by non-steroid anti-inflammatory drugs (NSAIDs). Here, we report additional safety use of Bif195 in 126 healthy humans undergoing an exercise-induced intestinal permeability challenge in a double-blinded, placebo-controlled randomised 6-week intervention trial. Intestinal permeability was assessed by urinary lactulose/rhamnose (L/R) ratio. L/R ratio, plasma intestinal fatty acid binding protein (I-FABP) and gastrointestinal symptom rating scale (GSRS) questionnaire were measured resting and after a 1 h treadmill challenge, prior to and at the end of the intervention. To be able to compare the equivalence of resting state at baseline, of this cohort of well-trained subjects, to non-trained subjects, a cohort of 63 healthy and non-trained subjects (<2 h/week of endurance sports) was included. Study subjects (well-trained) were 35.7% women with a mean age and body mass index (in kg/m2) of 35.0 years and 24.8, respectively. There were no differences between the Bif195 and placebo groups in effects on L/R ratio, I-FABP and GSRS questionnaire score. In addition, there were no differences between Bif195 and placebo in number of adverse events and change in cytokines, liver or kidney biomarkers. The exercise model successfully induced intestinal permeability by statistically significantly increasing L/R ratio by ~100% (P<0.0001) and cytokines after the exercise challenge. No significant difference was found between well-trained and non-trained subjects in baseline resting L/R ratio. In conclusion, the reported cytoprotective effects of Bif195 are unlikely to be primarily related to small bowel permeability, and the safety of Bif195 in individuals with increased permeability is supported by the present data. ClinicalTrials.gov: NCT03027583.

High Intensity Concentric-Eccentric Exercise Under Hypoxia Changes the Blood Metabolome of Trained Athletes.

The aim of this study was to determine alterations of the metabolome in blood plasma in response to concentric-eccentric leg exercise performed at a simulated altitude of 3,500 m. To do so, we recruited 11 well-trained subjects and performed an untargeted metabolomics analysis of plasma samples obtained before, 20 min after as well as on day 8 after five sets of maximal, concentric-eccentric leg exercises that lasted 90 s each. We identified and annotated 115 metabolites through untargeted liquid chromatography-mass spectrometry metabolomics and used them to further calculate 20 sum/ratio of metabolites. A principal component analysis (PCA) revealed differences in-between the overall metabolome at rest and immediately after exercise. Interestingly, some systematic changes of relative metabolite concentrations still persisted on day 8 after exercise. The first two components of the PCA explained 34% of the relative concentrations of all identified metabolites analyzed together. A volcano plot indicates that 35 metabolites and two metabolite ratios were significantly changed directly after exercise, such as metabolites related to carbohydrate and TCA metabolism. Moreover, we observed alterations in the relative concentrations of amino acids (e.g., decreases of valine, leucine and increases in alanine) and purines (e.g., increases in hypoxanthine, xanthine and uric acid). In summary, high intensity concentric-eccentric exercise performed at simulated altitude systematically changed the blood metabolome in trained athletes directly after exercise and some relative metabolite concentrations were still changed on day 8. The importance of that persisting metabolic alterations on exercise performance should be studied further.

Effects of wearable resistance load placement on neuromuscular activity and stride kinematics: A preliminary study.

Wearable resistance (WR) training is a modality that allows athletes to perform loaded sport-specific movements to develop force and power outputs. The acute responses by which WR works is still relatively unknown, and the effects of WR load and location of the load has not yet been examined. To investigate the acute neuromuscular and stride characteristic responses to different wearable resistance (WR) loads and placements on the calf muscles during high-speed running. Ten well-trained subjects completed a workout of ten sets of three 10s runs at 18km.h-1 (20s of rest between runs and one min between sets). Five conditions were tested: (1) unloaded control, (2) bilateral 0.75 vs. 1.5% body mass (BM) loading on the distal posterior calf, (3) bilateral proximal vs. distal loading of 1.5% BM positioned posteriorly, (4) bilateral anterior vs. posterior loading of 1.5% BM positioned distally, (5) unilateral loading of 1.5% BM on the distal posterior calf. Data were collected using Electromyography (EMG) and back-mounted GPS-embedded accelerometers. Magnitude of differences of within athlete and between muscle comparisons were calculated using effect sizes (ES) ± 90% confidence limits (CL). No substantial differences in accelerometry data were observed between any of the loaded conditions and the control. EMG activity was lower for proximal loading compared to the control for the gluteus maximus (ES±90%CL; -0.72±0.41), vastus lateralis (-0.89±0.47) and vastus medialis (VM) (-0.97±0.46). Anterior loading induced substantially lower EMG activity for the semitendinosus (-0.70±0.48) and VM (-0.64±0.39) muscles compared with the control. EMG activity of the VM (-0.73±0.46) muscle was also substantially lower for posterior loading compared to the control. Unilateral loading induced no substantial differences in EMG activity between the loaded and unloaded legs. This preliminary study has provided a rationale for the performance of further investigations into the effects of WR lower limb loading on stride characteristics and EMG activity from a chronic standpoint using a larger population.

Estimation of maximal oxygen uptake using the heart rate ratio method in male recreational football players.

Maximal oxygen uptake (VO2max) is associated with cardiovascular and metabolic health in the general population. The heart rate (HR) ratio method (HRratio) is a valid, easy and accessible method for estimating VO2max in well-trained subjects. This study examined the validity of using the HRratio to estimate VO2max in recreational football players in the untrained and trained states. Sixty-six participants (age 39.3 ± 5.8 years) were tested pre-training and 28 after 12 weeks, for VO2max assessment, running on a treadmill alternating speed (1 km h−1) and inclination (1%) increments every 30 s until exhaustion. Maximal HR (HRmax) was assessed directly with a multiple approach and estimated with selected equations. Resting HR (HRrest) was measured in supine position, after 15 min of rest. The HRratio method considers the product of HRmax/HRrest ratio by a theoretical proportionality factor (15 ml kg−1 min−1, TPF) to estimate VO2max. This population-specific proportionality factor (SPF) was 14.6 ± 2.6 ml kg−1 min−1. In the untrained state (n = 66), participants’ actual VO2max (41.3 ± 6.2 ml kg−1 min−1) was moderately lower (~ 2 ml kg−1 min−1) than the estimated VO2max using the TPF. A nonsignificant difference (0.7 ml kg−1 min−1) was found when the VO2max was estimated using the SPF. When using HRmax equations and the TPF, a small nonsignificant difference (~ 1.5 ml kg−1 min−1) was reported between actual and estimated VO2max. In the trained state (n = 28), the estimated VO2max values were not significantly different from the actual VO2max (44.2 ± 5.2 ml kg−1 min−1), with large effect sizes when considering TPF and estimated HRmax. The results of this study provide evidence of the applicability of HRratio in estimating VO2max in male adult/middle-aged recreational football players.

The Durability of an Intensive, Structured Education-Based Rehabilitation Protocol for Best Insulin Injection Practice: The ISTERP-2 Study.

IntroductionStudies on the durability of an intensive, structured education protocol on best insulin injection practice are missing for people with type 2 diabetes mellitus (T2DM). The aim of this study was to assess the durability of an intensive, structured education-based rehabilitation protocol on best insulin injection practice in well-trained subjects from our previous intensive, multimedia intervention study registered as the ISTERP-1 study. A total of 158 subjects with T2DM from the well-trained group of the 6-month-long ISTERP-1 study, all of whom had successfully attained lower glucose levels compared to baseline levels with lower daily insulin doses and with less frequent and severe hypoglycemic episodes, participated in the present investigation involving an additional 6-month follow-up period, called the ISTERP-2 study. MethodsParticipants were randomized into an intervention group and a control group, depending on whether they were provided or not provided with further education refresher courses for 6 months. At the end of the 6 months, the two groups were compared in terms of injection habits, daily insulin dose requirement, number of severe or symptomatic hypoglycemic events, and glycated hemoglobin (HbA1c) levels.ResultsDespite being virtually superimposable at baseline, the two groups behaved quite differently during the follow-up. The within-group analysis of observed parameters showed that the subjects in the intervention group maintained and even improved the good behavioral results learned during the ISTERP-1 study by further reducing both the rate of injection technique errors (p < 0.001) and size of lipohypertrophic lesions at injection sites (p < 0.02). Conversely, those in the control group progressively abandoned best practice, except for the use of ice-cold insulin and, consequently, had significantly higher HbA1c levels and daily insulin dose requirements at the end of the follow-up than at baseline (p < 0.05). In addition, as expected from all the above, the rate of hypoglycemic episodes also decreased in the intervention group (p < 0.05), resulting in a significant difference between groups after 6 months (p < 0.02). ConclusionOur data provide evidence that intensive, structured education refresher courses have no outstanding durability, so that repeated refresher courses, at least at 6-month intervals, are needed to have positive effects on people with T2DM, contributing not only to prevention but also to long-term rehabilitation.Trial RegistrationTrial Registration no. 118 bis/15.04.2018.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13300-021-01108-9.

Are We Exploring the Potential Role of Specialized Techniques in Muscle Hypertrophy?

Specialized resistance training techniques (e.g., drop-set, rest-pause) are commonly used by well-trained subjects for maximizing muscle hypertrophy. Most of these techniques were designed to allow a greater training volume (i.e., total repetitions×load), due to the supposition that it elicits greater muscle mass gains. However, many studies that compared the traditional resistance training configuration with specialized techniques seek to equalize the volume between groups, making it difficult to determine the inherent hypertrophic potential of these advanced strategies, as well as, this equalization restricts part of the practical extrapolation on these findings. In this scenario, the objectives of this manuscript were 1) to present the nuance of the evidence that deals with the effectiveness of these specialized resistance training techniques and - primarily - to 2) propose possible ways to explore the hypertrophic potential of such strategies with greater ecological validity without losing the methodological rigor of controlling possible intervening variables; and thus, contributing to increasing the applicability of the findings and improving the effectiveness of hypertrophy-oriented resistance training programs.

Task Learning Over Multi-Day Recording via Internally Rewarded Reinforcement Learning Based Brain Machine Interfaces.

Autonomous brain machine interfaces (BMIs) aim to enable paralyzed people to self-evaluate their movement intention to control external devices. Previous reinforcement learning (RL)-based decoders interpret the mapping between neural activity and movements using the external reward for well-trained subjects, and have not investigated the task learning procedure. The brain has developed a learning mechanism to identify the correct actions that lead to rewards in the new task. This internal guidance can be utilized to replace the external reference to advance BMIs as an autonomous system. In this study, we propose to build an internally rewarded reinforcement learning-based BMI framework using the multi-site recording to demonstrate the autonomous learning ability of the BMI decoder on the new task. We test the model on the neural data collected over multiple days while the rats were learning a new lever discrimination task. The primary motor cortex (M1) and medial prefrontal cortex (mPFC) spikes are interpreted by the proposed RL framework into the discrete lever press actions. The neural activity of the mPFC post the action duration is interpreted as the internal reward information, where a support vector machine is implemented to classify the reward vs. non-reward trials with a high accuracy of 87.5% across subjects. This internal reward is used to replace the external water reward to update the decoder, which is able to adapt to the nonstationary neural activity during subject learning. The multi-cortical recording allows us to take in more cortical recordings as input and uses internal critics to guide the decoder learning. Comparing with the classic decoder using M1 activity as the only input and external guidance, the proposed system with multi-cortical recordings shows a better decoding accuracy. More importantly, our internally rewarded decoder demonstrates the autonomous learning ability on the new task as the decoder successfully addresses the time-variant neural patterns while subjects are learning, and works asymptotically as the subjects' behavioral learning progresses. It reveals the potential of endowing BMIs with autonomous task learning ability in the RL framework.

Effectiveness of Training Prescription Guided by Heart Rate Variability Versus Predefined Training for Physiological and Aerobic Performance Improvements: A Systematic Review and Meta-Analysis

A systematic review and meta-analysis were performed to determine if heart rate variability-guided training (HRV-g), compared to predefined training (PT), maximizes the further improvement of endurance physiological and performance markers in healthy individuals. This analysis included randomized controlled trials assessing the effects of HRV-g vs. PT on endurance physiological and performance markers in untrained, physically active, and well-trained subjects. Eight articles qualified for inclusion. HRV-g training significantly improved maximum oxygen uptake (VO2max) (MD = 2.84, CI: 1.41, 4.27; p &lt; 0.0001), maximum aerobic power or speed (WMax) (SMD = 0.66, 95% CI 0.33, 0.98; p &lt; 0.0001), aerobic performance (SMD = 0.71, CI 0.16, 1.25; p = 0.01) and power or speed at ventilatory thresholds (VT) VT1 (SMD = 0.62, CI 0.04, 1.20; p = 0.04) and VT2 (SMD = 0.81, CI 0.41, 1.22; p &lt; 0.0001). However, HRV-g did not show significant differences in VO2max (MD = 0.96, CI −1.11, 3.03; p = 0.36), WMax (SMD = 0.06, CI −0.26, 0.38; p = 0.72), or aerobic performance (SMD = 0.14, CI −0.22, 0.51; p = 0.45) in power or speed at VT1 (SMD = 0.27, 95% CI −0.16, 0.70; p = 0.22) or VT2 (SMD = 0.18, 95% CI −0.20, 0.57; p = 0.35), when compared to PT. Although HRV-based training periodization improved both physiological variables and aerobic performance, this method did not provide significant benefit over PT.

The Effects of 10-Day Exogenous Ketone Consumption on Repeated Time Trial Running Performances: A Randomized-Control Trial

Introduction The effects of ketone salt supplementation on repeated short-distance running time trial (TT) performance in well-trained subjects remain unknown. Purpose To determine the effects of 10-day exogenous ketone salt supplementation on two consecutive 800 m running TTs in endurance-trained subjects. Methods Male and female subjects were randomly allocated to one of the following groups: Ketone (KET) (n = 16) or placebo (CON) (n = 16) (8 m, 8f per group). Subjects underwent two consecutive 800 m TTs before and after a 10-day treatment on a self-propelled treadmill. Time-to-completion of the first (TT1) and second (TT2) TT, the average time-to-completion (TTAVG), and blood lactate response during each TT was measured pre-post-treatment. Changes in blood ketone levels in response to a single dosing were measured pre- and post-treatment. Data was analyzed with a mixed factorial ANOVA with significance set to p < 0.05. Results KET demonstrated a faster TTAVG from pre- to post-treatment (-6.1 ± 8.9 s; p = 0.02) while CON showed no change. At pre- and post-treatment, CON showed no acute changes in blood ketones after a single-dosing while KET demonstrated a significant increases (Pretreatment = +0.4 ± 0.3 mmol/L; p < 0.001; Post-Treatment = +0.4 ± 0.4 mmol/L; p < 0.001). These acute single-dosing responses in blood ketone levels for KET did not change between pre- and post-treatment. There were no interactions for blood lactate response to exercise or fatigue index. Conclusions In trained subjects, 10 days of ketone salt supplementation does not affect performance in an initial bout of short-distance running, such as during TT1. However, ergogenic effects may be observed under fatigue conditions for example during a repeated running bout.

The Effects Of One-week Exogenous Ketone Consumption On Short Distance Time Trial Running Performance

Currently, there is equivocal knowledge concerning the effects of ketone salt supplementation on short distance running time trial (TT) performance in well-trained subjects. PURPOSE: To determine the effects of one-week exogenous ketone salt supplementation on 800m running TT performance during non-fatigued and pre-exhaustive states in endurance-trained subjects. METHODS: In a randomized, double-blind, placebo-controlled study, endurance-trained male and female participants were allocated to one of the following treatment groups for 8 days following an initial familiarization visit: Ketone supplementation (KET) (n=16) or placebo control (CON) (n=16). Subjects underwent two consecutive 800m TT before and after the 8-day treatment period on a self-propelled, non-motorized treadmill. Time-to-completion of the first (TT1) and second (TT2) TTs, the average time-to-completion across both TTs, and blood lactate response during the TTs were measured pre- and post-treatment. A mixed factorial ANOVA was used for data analysis. RESULTS: KET alone exhibited a significant increase in blood β-hydroxybutyrate from pre-post-treatment (p<0.05). A group x time interaction was only detected for TT2 performance (p<0.05) but not TT1. There was no pre- to post-treatment change in TT1 performance in either group. CON demonstrated no change in TT2 performance from pre- to post-treatment; however, KET improved TT2 performance as reflected by a 3.7% faster time-to-completion from pre- to post-treatment (p<0.05). When examining the average time-to-completion across both TTs, there was a significant group x time interaction (p=0.04). CON showed no change while KET demonstrated a faster average time-to-completion from pre- to post-treatment (p<0.05). Blood lactate response to TTs decreased (p<0.05) in KET but not CON. CONCLUSIONS: In endurance-trained subjects, ketone salt supplementation does not appear to affect short-distance running TT performance in a non-fatigued state reflective of competition scenarios. However, ergogenic effects may be observed in high-intensity exercise when some level of exhaustion or energy substrate depletion is experienced prior, such as during training or prolonged, intermittently high-intensity sporting bouts.

Wheelchair Propulsion Technique at Different Speeds

To study wheelchair propulsion technique at different speeds, five well-trained subjects propelled a wheelchair on a treadmill. Measurements were made at four belt speeds of 0.56-1.39 m/s and against slopes of 2 and 3 degrees. Cardiorespiratory data were collected. Three consecutive strokes were filmed. Using markers on subject, wheelchair and treadmill frame a kinematic analysis was performed. Considerable inter-individual differences in propulsion style were found, but also general changes relative to speed occurred in the group as a whole. Cycle time decreased with speed, predominantly as the result of a shorter push time while push angle remained constant and the movement ranges of trunk and arms shifted with speed. It is concluded that despite different propulsion styles, general and continuous adaptations to speed changes occurred, mainly by flexion of the trunk and arms.

Post-exercise Endothelium-Dependent Vasodilation Is Dependent on Training Status.

The effect of training status on post-exercise flow-mediated dilation (FMD) is not well characterized. We tested the hypothesis that the more trained the subjects, the lower the reduction in FMD after an acute bout of aerobic exercise. Forty-seven men (mean ± SD, age: 20.1 ± 1.2 years, body mass: 75.5 ± 5.1 kg, height 178.1 ± 5.4 cm) were divided into five groups with different training characteristics (sedentary, two different groups of active subjects, two different groups of well-trained subjects – runners and weightlifters). Brachial artery FMD (blood pressure cuff placed around the arm distal to the probe with the proximal border adjacent to the medial epicondyle; 5 min at a pressure of 220 mmHg) was assessed before and during 3 min immediately after a bout of cycling exercise at a relative intensity of 170 bpm [(physical work capacity (PWC170)]. At baseline, a progressive increase in FMD was observed in the participants with the higher training status, if the training remained moderate. Indeed, FMD was reduced in runners and weightlifters compared to those who were moderately trained. After PWC170, FMD did not significantly change in sedentary and highly trained runners, significantly increased in the two groups of active subjects but significantly decreased in highly trained weightlifters. These results showed that endothelium-dependent vasodilation evaluated using brachial FMD is maintained or improved following acute aerobic exercise in moderately trained participants, but not in well-trained participants, especially if they are engaged in resistance training.

Exercise-Induced Circulating Hematopoietic Stem and Progenitor Cells in Well-Trained Subjects.

It has been proposed that exercise-induced systemic oxidative stress increases circulating hematopoietic stem and progenitor cell (HPC) number in active participants, while HPC clonogenicity is reduced post-exercise. However, HPCs could be protected against exercise-induced reactive oxygen species in a trained state. Therefore, we characterized the acute exercise-induced HPC profile of well-trained participants including cell number, clonogenicity, and clearance. Twenty-one healthy, well-trained participants—12 runners, 9 cyclists; age 30.0 (4.3) years—performed a strenuous acute exercise session consisting of 4 bouts of 4-min high-intensity with 3-min low-intensity in-between, which is known to elicit oxidative stress. Average power/speed of intense phases was 85% of the peak achieved in a previous incremental test. Before and 10 min after exercise, CD34+/45dim cell number and clonogenicity, total oxidative (TOC), and antioxidative (TAC) capacities, as well as CD31 expression on detected HPCs were investigated. TOC significantly decreased from 0.093 (0.059) nmol/l to 0.083 (0.052) nmol/l post-exercise (p = 0.044). Although HPC proportions significantly declined below baseline (from 0.103 (0.037)% to 0.079 (0.028)% of mononuclear cells, p < 0.001), HPC concentrations increased post-exercise [2.10 (0.75) cells/μl to 2.46 (0.98) cells/μl, p = 0.002] without interaction between exercise modalities, while HPC clonogenicity was unaffected. Relating HPC concentrations and clonogenicity to exercise session specific (anti-) oxidative parameters, no association was found. CD31 median fluorescent intensity expression on detected HPCs was diminished post-exercise [from 1,675.9 (661.0) to 1,527.1 (558.9), p = 0.023] and positively correlated with TOC (rrm = 0.60, p = 0.005). These results suggest that acute exercise-reduced oxidative stress influences HPC clearance but not mobilization in well-trained participants. Furthermore, a well-trained state protected HPCs’ clonogenicity from post-exercise decline.

The Effectiveness of Frequency-Based Resistance Training Protocols on Muscular Performance and Hypertrophy in Trained Males: A Critically Appraised Topic.

Clinical Scenario: Manipulation of exercise variables in resistance training (RT) is an important component in the development of muscular strength, power, and hypertrophy. Currently, most research centers on untrained or recreationally trained subjects. This critically appraised topic focuses on studies that center on the well-trained subject with regard to frequency of training. Clinical Question: In well-trained male subjects, is there an association between RT frequency and the development of muscular strength and hypertrophy? Summary of Key Findings: Four studies met the inclusion criteria and were included for analysis. All studies showed that lower-frequency training could elicit muscular strength and hypertrophy increases. One study suggested that a higher frequency compared with a lower frequency may provide a slight benefit to hypertrophic development. One study reported a greater level of delayed onset muscle soreness with lower frequency training. The 4 studies demonstrate support for the clinical question. Clinical Bottom Line: Current evidence suggests that lower-frequency RT produces equal to greater improvements on muscular strength and hypertrophy in comparison to higher-frequency RT when volume is equated. The evidence is particularly convincing when lower-frequency RT is associated with a total-body training protocol in well-trained male subjects. Strength of Recommendation: There is moderate-to-strong evidence to suggest that lower-frequency RT, when volume is equated, will produce equal to greater improvements on muscular strength and hypertrophy in comparison to higher-frequency RT.

Can Backward Sled Towing Potentiate Sprint Performance?

Monaghan, DJ and Cochrane, DJ. Can backward sled towing potentiate sprint performance? J Strength Cond Res 34(2): 345-354, 2020-The objectives of this study were to determine whether backward sled towing can elicit a postactivation potentiation response to enhance forward 5-m sprint performance and to determine whether sled loading through a reduction in velocity can elicit an improvement in 5-m sprint performance. A randomized design was used to examine the effects of forward and backward sled tow loading of 35 and 55% reduction of individual's maximal velocity (rVelmean) on 5-m sprint performance. Eighteen well-trained male subjects performed 4 intervention sessions (55% rVelmean backward; 55% rVelmean forward; 35% rVelmean backward; and 35% rVelmean forward) separated by a minimum of 24 hours. Intervention sessions included baseline unresisted 5-m sprints, followed by 3 loaded sled tows over a distance of 3.2 m or 5 m for heavy and light loads, respectively. An unresisted 5-m sprint was completed after 6 and 12 minutes of rest. Mean sprint velocity, electromyography, sprint kinematic, and temporal data were collected during each session. Sled towing, irrespective of load or rest period, produced no significant change in 5-m sprint velocity (p > 0.05). In addition, there were no significant changes in electromyography, kinetic, and temporal data; however, current findings support previous research of confirming muscle activation and vertical force production during sprint acceleration. It is unclear whether individualizing a reduction in velocity is a superior method to percent body mass for optimizing sled loading in well-trained male subjects.

Coenzyme Q10 status, glucose parameters, and antioxidative capacity in college athletes

BackgroundGlycemia is related to energy production during exercise. Coenzyme Q10 is an antioxidant that participates in adenosine triphosphate synthesis in mitochondria. The aim of this study was to investigate the level of coenzyme Q10, glucose parameters, and antioxidant capacity in athletes.MethodsThis study was designed as a cross-sectional study. Well-trained college athletes (n = 43) and age-gender matched healthy subjects (n = 25) were recruited from a college. The levels of glucose parameters, oxidative stress, antioxidant enzymes activity, Trolox equivalent antioxidant capacity (TAC), and coenzyme Q10 status were measured in the present study.ResultsThe athletes had a significantly lower level of white blood cells (WBC) coenzyme Q10 than the healthy subjects (0.34 ± 0.24 vs. 0.65 ± 0.43 nmol/g, p < 0.01); however, no significant difference was detected in plasma coenzyme Q10 between the two groups. Regarding the glucose parameters, the athletes had significantly higher values for HbA1c (5.5 ± 0.3 vs. 5.3 ± 0.3%, p < 0.05) and quantitative insulin sensitivity check index (QUICKI, 0.37 ± 0.03 vs. 0.34 ± 0.03, p < 0.05), and lower homeostatic model assessment-insulin resistance (HOMA-IR, 1.5 ± 0.8 vs. 2.9 ± 3.8, p < 0.05) than the healthy subjects. A higher level of TAC was found in the athletes (serum, 5.7 ± 0.3 vs. 5.4 ± 0.2 mM Trolox; erythrocyte, 10.5 ± 0.6 vs. 10.0 ± 0.5 mM Trolox, p < 0.05). In addition, WBC coenzyme Q10 status was significantly correlated with catalase activity (r = 0.56, p < 0.01), GPx activity (r = 0.56, p < 0.01), serum TAC (r = 0.54, p < 0.01), fasting glucose (β = − 1.10, p < 0.01), HbA1c (β = − 0.82, p < 0.01), HOMA-IR (β = − 1.81, p < 0.01), and QUICK (β = 0.08, p < 0.01).ConclusionsAthletes may suffer from a marginal coenzyme Q10 deficiency, and the level was related to glycemic control and antioxidant capacity. Further interventional studies are needed to clarify an adequate dose of coenzyme Q10 supplementation in athletes to optimize their coenzyme Q10 status and athletic performance or recovery during exercise.

Effects of protein intake prior to carbohydrate-restricted endurance exercise: a randomized crossover trial

BackgroundDeliberately training with reduced carbohydrate availability, a paradigm coined training low, has shown to promote adaptations associated with improved aerobic capacity. In this context researchers have proposed that protein may be ingested prior to training as a means to enhance the protein balance during exercise without spoiling the effect of the low carbohydrate availability. Accordingly, this is being practiced by world class athletes. However, the effect of protein intake on muscle protein metabolism during training low has not been studied.This study aimed to examine if protein intake prior to exercise with reduced carbohydrate stores benefits muscle protein metabolism in exercising and non-exercising muscles.MethodsNine well-trained subjects completed two trials in random order both of which included a high-intensity interval ergometer bike ride (day 1), a morning (day 2) steady state ride (90 min at 65% VO2peak, 90ss), and a 4-h recovery period. An experimental beverage was consumed before 90ss and contained either 0.5 g whey protein hydrolysate [WPH]/ kg lean body mass or flavored water [PLA]. A stable isotope infusion (L-[ring-13C6]-phenylalanine) combined with arterial-venous blood sampling, and plasma flow rate measurements were used to determine forearm protein turnover. Myofibrillar protein synthesis was determined from stable isotope incorporation into the vastus lateralis.ResultsForearm protein net balance was not different from zero during 90ss exercise (nmol/100 ml/min, PLA: 0.5 ± 2.6; WPH: 1.8, ± 3.3) but negative during the 4 h recovery (nmol/100 ml/min, PLA: − 9.7 ± 4.6; WPH: − 8.7 ± 6.5); no interaction (P = 0.5) or main effect of beverage (P = 0.11) was observed. Vastus lateralis myofibrillar protein synthesis rates were increased during 90ss exercise (+ 0.02 ± 0.02%/h) and recovery (+ 0.02 ± 0.02%/h); no interaction (P = 0.3) or main effect of beverage (P = 0.3) was observed.ConclusionWe conclude that protein ingestion prior to endurance exercise in the energy- and carbohydrate-restricted state does not increase myofibrillar protein synthesis or improve net protein balance in the exercising and non-exercising muscles, respectively, during and in the hours after exercise compared to ingestion of a non-caloric control.Trial registrationclinicaltrials.gov, NCT01320449. Registered 10 May 2017 – Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03147001