Estimation of Heat Production Rate using Thermal Data During Exercise in Indoor Environments: A Study of Heat Storage Rate in Male Athletes.

The increasing preference for indoor exercise spaces highlights the relationship between indoor thermal environments and physiological responses, particularly concerning thermal comfort during physical activity. Determining the metabolic heat production rate during exercise is essential for optimizing the thermal comfort, well-being, and performance of individuals engaged in physical activities. This value can be determined during the activity using several methods, including direct calorimetry measurement, indirect calorimetry that uses analysis of respiratory gases, or approximations using collected data such as speed, body mass, and heart rate. The study aimed to calculate the metabolic heat production rate by infrared thermal evaluation (ITE) based on the body's thermal balance approach and compare it with the values determined by indirect calorimetry (IC). Fourteen participants volunteered for the study, using a cycling ergometer in a controlled climatic chamber. After the familiarization sessions, maximal O2 intake levels (VO2max) were determined through maximal graded exercise tests. Subsequently, constant work rate exercise tests were performed at 60% of VO2max for 20 min. The metabolic heat production rates were calculated by IC and ITE for each athlete individually. Respiratory gases were used to determine IC, while body skin and core temperatures, along with physical environmental data, were applied to calculate ITE using the human body thermal balance approximation of ASHRAE. According to the results, heat storage rates were misleading among the body's heat transfer modes, particularly during the first 8 min of the exercise. ITE showed a moderate level of correlation with IC (r: 0.03-0.86) with a higher level of dispersion relative to the mean (CV%: 12-84%). Therefore, a new equation (ITEnew) for the heat storage rates was proposed using the experimental data from this study. The results showed that ITEnew provided more precise estimations for the entire exercise period (p > 0.05). Correlations between ITEnew and IC values were consistently strong throughout the exercise period (r: 0.62-0.85). It can be suggested that ITEnew values can predict IC during the constant work rate steady-state exercise.

Development potentials of commonly used high-intensity training strategies on central and peripheral components of maximal oxygen consumption.

The aim of this study was to reveal the development potentials of five high-intensity training models on central and peripheral components of maximal oxygen consumption (VO2max). Following VO2max determination, maximal cardiac output (Qmax), maximal stroke volume (SVmax), and maximal arteriovenous O2 difference (a-vO2diff_max) were analysed. Short-interval- (short-HIIT), long-interval (long-HIIT), alternating work-rate continuous (alter-HIT), constant work-rate continuous (const-HIT), and sprint interval (SIT) sessions were performed on separate days with iso-effort and iso-time methods. Time spent (tspent) at > 95% of VO2max was the highest in long-HIIT (p < 0.05). The tspent at > 90% of Qmax was higher in alter-HIT than long-HIIT and SIT (p < 0.05), while there was no significant difference for tspent at > 90% of SVmax amongst high-intensity trainings. The tspent at > 90% of a-vO2diff_max was higher in short-HIIT and long-HIIT than other modalities (p < 0.05). It can be said that continuous modalities seem to have a higher potential to improve central part of VO2max, while interval modalities may be better to develop peripheral component.

The importance of the verification phase following an incremental exercise to ensure maximum oxygen consumption.

BACKGROUND: The purpose of this study was to analyze cardiac output (Qc), stroke volume (SV), heart rate (HR), and arterio-venous O2 difference (a-vO2diff) responses throughout a graded exercise test (GXT) and verification phase (VP) to examine whether SV decrement during the GXT is a main factor for underestimation of the maximal O2 uptake (V̇O2max), or not. METHODS: Seven well-trained male cyclists volunteered for this study (V̇O2max: 61.7±6.13 mL∙min-1∙kg-1). Following submaximal tests, participants were asked to perform GXT until exhaustion. Then, multisession verifications were performed on different days using ±3% constant work rates. The highest 30-second mean of V̇O2 was considered as the V̇O2max and corresponding external power as peak power output (PPO). The Qc, SV, HR, and a-vO2diff responses were evaluated at both GXT and VP by nitrous-oxide rebreathing method. After repeated-measures analyses, possible significant differences were investigated by LSD/Wilcoxon. RESULTS: It was shown that the HR and a-vO2diff reached their potentially highest values at the end of the both GXT and VP (192.9±8.8 vs. 190.7±7.9 bpm; 17.1±1.6 vs. 16.9±1.1%, respectively; P>0.05); however, SV (128.8±11.2 vs. 137.3±11.2 mL; P=0.029) and Qc (24.8±2.02 vs. 26.2±2.71 L·min-1; P=0.046) were lower at GXT when compared to the VP. V̇O2 means were, therefore, higher in VP when compared to the GXT (61.7±6.13 vs. 59.1±6.2 mL∙min-1∙kg-1; P=0.041). CONCLUSIONS: The GXT provided only a peak V̇O2 but not the V̇O2max. Consequently, the real V̇O2max and PPO could be provided by only VP administrations. This is likely to result from the lower Qc and SV responses observed from a prolonged incremental test protocol when compared to short bouts of constant work rate trials.

Moderate Intensity Intermittent Exercise Modality May Prevent Cardiovascular Drift.

Cardiovascular drift (CV-Drift) may occur after the ~10th min of submaximal continuous exercising. The purpose of this study was to examine whether CV-Drift is prevented by an intermittent exercise modality, instead of a continuous exercise. Seven well-trained male cyclists volunteered to take part in the study ( V ˙ O2max: 61.7 ± 6.13 mL·min-1·kg-1). Following familiarization sessions, athletes' individual maximal O2 consumption ( V ˙ O2max), maximum stroke volume responses (SVmax), and cardiac outputs (Qc) were evaluated by a nitrous-oxide re-breathing system and its gas analyzer. Then, continuous exercises were performed 30 min at cyclists' 60% V ˙ O2max, while intermittent exercises consisted of three 10 min with 1:0.5 workout/recovery ratios at the same intensity. Qc measurements were taken at the 5th, 9th, 12nd, 15th, 20th, 25th, and 30th min of continuous exercises versus 5th and 10th min of workout phases of intermittent exercise modality. Greater than a 5% SV decrement, with accompanying HR, increase, while Qc remained stable and was accepted as CV-Drift criterion. It was demonstrated that there were greater SV responses throughout intermittent exercises when compared to continuous exercises (138.9 ± 17.9 vs. 144.5 ± 14.6 mL, respectively; p ≤ 0.05) and less HR responses (140.1 ± 14.8 vs. 135.2 ± 11.6 bpm, respectively; p ≤ 0.05), while mean Qc responses were similar (19.4 ± 2.1 vs. 19.4 ± 1.5 L, respectively; p > 0.05). Moreover, the mean times spent at peak SV scores of exercise sessions were greater during intermittent exercise (1.5 vs. 10 min) (p < 0.001). In conclusion, intermittent exercises reduce CV-Drift risk and increases cardiac adaptation potentials of exercises with less physiological stress.

Associations between Thermal and Physiological Responses of Human Body during Exercise.

In this study, thermal behaviours of the athletes were investigated with respect to thermal comfort and exercise intensity. The relationship between an index for analysing thermal comfort (Predicted Mean Vote: PMV) and Rating of Perceived Exertion (RPE) which shows exercise intensity and exhaustion level was evaluated. Eleven moderately trained male athletes ( V ˙ O2max 54 ± 9.9 mL∙min-1∙kg-1) had volunteered for the study (age: 22.2 ± 3.7 years; body mass: 73.8 ± 6.9 kg; height: 181 ± 6.3 cm; Body surface area (BSA): 1.93 ± 0.1 m²; body fat: 12.6% ± 4.2%; V ˙ O2max: 54 ± 9.9 mL∙min-1∙kg-1). Experiments were carried out by using a cycle ergometer in an air-conditioned test chamber which provided fresh air and had the ability to control the temperature and relative humidity. The study cohort was divided into two groups according to maximal oxygen consumption levels of the participants. Statistical analyses were conducted with the whole study cohort as well as the two separated groups. There was a moderate correlation between PMV and RPE for whole cohort (r: -0.51). When the whole cohort divided as low and high aerobic power groups, an average correlation coefficient at high oxygen consumption cohort decreased to r: -0.21, while the average correlation coefficient at low oxygen consumption cohort increased to r: -0.77. In conclusion, PMV and RPE have a high correlation in less trained participants, but not in the more trained ones. The case may bring to mind that thermal distribution may be better in high aerobic power group in spite of high RPE and thus the relation between PMV and RPE is affected by exercise performance status.

Re-Evaluation of Old Findings on Stroke Volume Responses to Exercise and Recovery by Nitrous-Oxide Rebreathin.

It is important to verify the old findings of Cumming (1972) and Goldberg and Shephard (1980) who showed that stroke volume (SV) may be higher during recovery rather than during exercise, in order to organize the number of intervals throughout training sessions. The purpose of this study was to re-evaluate individual SV responses to various upright cycling exercises using the nitrous-oxide rebreathing method. Nine moderate to well-trained male athletes volunteered to take part in the study (maximal O2 uptake (VO2max): 60.2 ± 7 mL⋅min-1⋅kg-1). Workloads ranging from 40-100% of VO2max were applied to determine individual peak SV (SVpeak) response. Results showed that SV responses were higher during exercise compared to recovery in all exercise loads from 40-100% of VO2max. Mean SV responses to individual SVpeak loads were also higher during exercise compared to recovery (122.9 ± 2.5 versus 105.3 ± 5.93 mL). The highest SV responses to 10 min exercises of 40-70% of VO2max were obtained in the 5th or 7.5th min of each stage (p≤0.05). Meanwhile, during 5 min exercises between 80-100% of VO2max, peak SV responses were observed in the 3rd min of loading (p≤0.05). In conclusion, individual SVpeak levels encountered over wide exercise intensity ranges showed that SVpeak development may also be correlated to exercise intensity corresponding to individual SVpeak loads.

Shorter intervals at peak SV vs.V̇O2max may yield high SV with less physiological stress.

The purpose of this study was to evaluate whether greater and sustainable stroke volume (SV) responses may be obtained by exercise intensities corresponding to peak SV (SVpeak) vs. maximal O2 consumption (VO2max), and short vs. long intervals (SI vs. LI). Nine moderate- to well-trained male athletes competing at regional level specialists of cyclist, track and field volunteered to take part in the study (VO2max: 59.7 ± 7.4 mL·min(-1)·kg(-1)). Following familiarisation sessions, VO2max was determined, and then SVpeak was evaluated using exercise intensities at 40%-100% of VO2max by nitrous-oxide rebreathing (N2ORB) method. Then each separate participant exercised wattages corresponding to individual VO2max and SVpeak during both SI (SIVO2max and SI(SVpeak)) and LI (LIVO2max and LI(SVpeak)) workouts on a cycle ergometer. Main results showed that both SIVO2max and SI(SVpeak) yielded greater SV responses than LIVO2max and LI(SVpeak) (p ≤ 0.05). Mean SV responses were greater in LI(SVpeak) than in LIVO2max (p ≤ 0.05), but there was no statistical difference between SI(SVpeak) and SIVO2max. However, there was significantly less physiological stress based on VO2, respiratory exchange ratio, heart rate and rate of perceived exhaustion in SVpeak than in [Formula: see text] intensities (p ≤ 0.05). Moreover, SV responses at exercise phases increased in the early stages and remain stable until the end of SIVO2max and SI(SVpeak) workouts (p > 0.05), while they were gradually decreasing in LIVO2max and LI(SVpeak) sessions (p ≤ 0.05). In conclusion, if the aim of a training session is to improve SVpeak with less physiological stress, SI(SVpeak) seems a better alternative than other modalities tested in the present study.

Effects of three different stretching techniques on vertical jumping performance.

The aim of this study was to evaluate 3 different flexibility techniques: (a) ballistic stretching (BS), (b) proprioceptive neuromuscular facilitation stretching (PNF) + BS, and (c) PNF + static stretching (SS) on vertical jump (VJ) performance and to determine the most appropriate stretching method during warm-up period before explosive force disciplines. One hundred voluntary male athletes participated in this study. All subjects performed aerobic warm-up (5-minute jog) followed by BS (5 seconds for each stretching exercise), PNF + BS (PNF performed followed by 5 seconds of BS), and PNF + SS (PNF performed followed by 30 seconds of SS) treatment protocol, respectively in the same day. Each stretching treatment was applied for 4 sets bilaterally. In all stretching treatments, lumbar extensor, gluteus maximus, and hamstring muscles were stretched with a single stretching exercise. After a 2-minute brief rest period, participants performed 3 trials of VJ test followed by one of the treatment protocols. Vertical jump performance was evaluated by countermovement jump (CMJ). Participants were divided into 3 groups according to their flexibility and prejump performances after warm-up. For each individual group and the whole group, after all treatments, differences in CMJ values were obtained (p ≤ 0.05). Ballistic stretching increased the VJ performance in the groups with low and average flexibility, poor prejumping performance, and also in the whole group (p ≤ 0.05). Proprioceptive neuromuscular facilitation stretching + BS affected VJ performance in the group of participants with high flexibility (p ≤ 0.05). Proprioceptive neuromuscular facilitation + SS decreased VJ performance in groups of participants with high flexibility, moderate, and high prejumping performance and in whole group (p ≤ 0.05). Ballistic stretching method increased VJ height, therefore seems to be more suitable than PNF + SS and PNF + BS before events that rely on explosive power as a part of warm-up period.

An elliptical trainer may render the Wingate all-out test more anaerobic.

The purpose of this study was to evaluate the contribution of the 3 main energy pathways during a 30-second elliptical all-out test (EAT) compared with the Wingate all-out test (WAT). Participants were 12 male team sport players (age, 20.3 ± 1.8 years; body mass, 74.8 ± 12.4 kg; height, 176.0 ± 9.10 cm; body fat, 12.1 ± 1.0%). Net energy outputs from the oxidative, phospholytic, and glycolytic energy systems were calculated from oxygen uptake data recorded during 30-second test, the fast component of postexercise oxygen uptake kinetics, and peak blood lactate concentration, respectively. In addition, mechanical power indices were calculated. The main results showed that compared with WAT, EAT was characterized by significantly lower absolute and relative contributions of the oxidative system (16.9 ± 2.5 J vs. 19.8 ± 4.9 J; p ≤ 0.05 and 11.2 ± 1.5% vs. 15.7 ± 3.28%; p ≤ 0.001). In addition, significantly greater absolute and relative contributions of the phospholytic system (66.1 ± 15.8 J vs. 50.7 ± 15.9 J; p ≤ 0.01 and 43.8 ± 6.62% vs. 39.1 ± 6.87%; p ≤ 0.05) and a significantly greater absolute contribution of the glycolytic system (68.6 ± 18.4 J vs. 57.4 ± 13.7 J; p ≤ 0.01) were observed in EAT compared with WAT. Finally, all power indices, except the fatigue index, were significantly greater in EAT than WAT (p ≤ 0.05). Because of the significantly lower aerobic contribution in EAT compared with WAT, elliptical trainers may be a good alternative to cycle ergometers to assess anaerobic performance in athletes involved in whole-body activities.

Effects of a Dynamic Warm-Up, Static Stretching or Static Stretching with Tendon Vibration on Vertical Jump Performance and EMG Responses.

The purpose of this study was to investigate the short-term effects of static stretching, with vibration given directly over Achilles tendon, on electro-myographic (EMG) responses and vertical jump (VJ) performances. Fifteen male, college athletes voluntarily participated in this study (n=15; age: 22±4 years old; body height: 181±10 cm; body mass: 74±11 kg). All stages were completed within 90 minutes for each participant. Tendon vibration bouts lasted 30 seconds at 50 Hz for each volunteer. EMG analysis for peripheral silent period, H-reflex, H-reflex threshold, T-reflex and H/M ratio were completed for each experimental phases. EMG data were obtained from the soleus muscle in response to electro stimulation on the popliteal post tibial nerve. As expected, the dynamic warm-up (DW) increased VJ performances (p=0.004). Increased VJ performances after the DW were not statistically substantiated by the EMG findings. In addition, EMG results did not indicate that either static stretching (SS) or tendon vibration combined with static stretching (TVSS) had any detrimental or facilitation effect on vertical jump performances. In conclusion, using TVSS does not seem to facilitate warm-up effects before explosive performance.

Mechanically braked elliptical Wingate test: modification considerations, load optimization, and reliability.

The 30-second, all-out Wingate test evaluates anaerobic performance using an upper or lower body cycle ergometer (cycle Wingate test). A recent study showed that using a modified electromagnetically braked elliptical trainer for Wingate testing (EWT) leads to greater power outcomes because of larger muscle group recruitment. The main purpose of this study was to modify an elliptical trainer using an easily understandable mechanical brake system instead of an electromagnetically braked modification. Our secondary aim was to determine a proper test load for the EWT to reveal the most efficient anaerobic test outcomes such as peak power (PP), average power (AP), minimum power (MP), power drop (PD), and fatigue index ratio (FI%) and to evaluate the retest reliability of the selected test load. Delta lactate responses (ΔLa) were also analyzed to confirm all the anaerobic performance of the athletes. Thirty healthy and well-trained male university athletes were selected to participate in the study. By analysis of variance, an 18% body mass workload yielded significantly greater test outcomes (PP = 19.5 ± 2.4 W·kg, AP = 13.7 ± 1.7 W·kg, PD = 27.9 ± 5 W·s, FI% = 58.4 ± 3.3%, and ΔLa = 15.4 ± 1.7 mM) than the other (12-24% body mass) tested loads (p < 0.05). Test and retest results for relative PP, AP, MP, PD, FI%, and ΔLa were highly correlated (r = 0.97, 0.98, 0.94, 0.91, 0.81, and 0.95, respectively). In conclusion, it was found that the mechanically braked modification of an elliptical trainer successfully estimated anaerobic power and capacity. A workload of 18% body mass was optimal for measuring maximal and reliable anaerobic power outcomes. Anaerobic testing using an EWT may be more useful to athletes and coaches than traditional cycle ergometers because a greater proportion of muscle groups are worked during exercise on an elliptical trainer.

Relationship between ace genotype and short duration aerobic performance development.

We have previously demonstrated that, ACE D allele may be related with a better performance in short duration aerobic endurance in a homogeneous cohort with similar training backgrounds. We aimed to study the variation in the short-duration aerobic performance development amongst ACE genotypes in response to identical training programs in homogeneous populations. The study group consisted of 186 male Caucasian non-elite Turkish army recruits. All subjects had undergone an identical training program with double training session per day and 6 days a week for 6 months. Performances for middle distance runs (2,400 m) were evaluated on an athletics track before and after the training period. ACE gene polymorphisms were studied by PCR analysis. The distribution of genotypes in the whole group was 16.7% II, n=31; 46.2% ID, n=86; 37.1% DD, n=69. Subjects with ACE DD genotype had significantly higher enhancement than the ID (P<0.01) and II (P<0.05) genotype groups. Around 2,400 m performance enhancement ratios showed a linear trend as ACE DD>ACE ID>ACE II (P value for Pearson chi2=0.461 and P value for linear by linear association=0.001). ACE DD genotype seems to have an advantage in development in short-duration aerobic performance. This data in unison with the data that we have obtained from homogenous cohorts previously is considered as an existence of threshold for initiation of ACE I allele effectiveness in endurance performance. This threshold may be anywhere between 10 and 30 min with lasting maximal exercises.

ACE genotype may have an effect on single versus multiple set preferences in strength training.

A polymorphic variant of the human angiotensin converting enzyme (ACE) gene was identified. The 'D' (rather than 'I') variant was associated with improvements in strength related to physical training. We set out to determine whether the response to different patterns of strength training might also differ. Ninty-nine Caucasian male non-elite athletes were randomly allocated into one of three groups: 31 non-training/control (CG: 31), single-set (SSG: 35) and multiple-set (MSG: 33). SSG and MSG trained three times a week for 6 weeks. Both training groups were underwent a strength-training program with two mesocycles (12-15 repetition maximum (RM) and 8-12 RM mesocycles). One RM loads in half squat and bench press were assessed before training and after the first and second mesocycles. ACE polymorphisms analysed by polymerase chain reaction (PCR) methods. Subjects with ACE II genotype in the MST group had improved strength development in 12-15 RM, while SST and MST groups had similar gains in 8-12 RM. Subjects with ACE DD genotype in both the SSG and the MSG had similar benefits from both 12-15 RM and 8-12 RM. Strength gains for subjects with ACE ID genotype in the SSG were similar to MSG gains in response to 8-12 RM loads but not with 12-15 RM loads. Additionally, subjects with DD genotype had superior strength gains in both strength training groups. Tailoring strength training programmes (single-set vs. multiple set) according to the athlete's ACE genotype may be advantageous.

Association between the ACE I/D gene polymorphism and physical performance in a homogeneous non-elite cohort.

BACKGROUND: I/D polymorphism of the ACE gene may be associated with better endurance performance and a stronger response to exercise training. The aim of this study was to investigate the association between ACE gene polymorphism and athletic performance in a homogeneous cohort. METHODS: Eighty-eight male non-elite Caucasian Turkish athletes with similar training backgrounds for at least for 6 months were studied for ACE gene polymorphisms by PCR analysis. Performance on the 60-meter sprint and middle-distance running tests were evaluated. RESULTS: The distributions of the ACE I/D genotypes were 20.5%, 40.9%, and 38.6% for II, ID, and DD polymorphisms in the whole group (N = 88), respectively. The ACE DD genotype frequency was significantly higher in the superior group (56.7%) than in the poor (37.9%) and mediocre (20.7%) group in middle-distance running performance (chi2 = 11.778; p = 0.019). CONCLUSION: The ACE DD genotype may be related to better short-duration aerobic endurance performance. Larger homogeneous cohorts may help clarify the association between ACE I/D polymorphism and physical performance.