Phase angle as an indicator of body composition and physical performance in handball players

BACKGROUND

Phase angle (PhA), obtained from the bioimpedance analysis, is widely used in clinical situations and in sports. This study evaluated the association between PhA with body composition and physical performance of handball athletes.

METHODS

43 national-level players (22.19 ± 3.86 years) of both sexes were evaluated regarding anthropometry, body composition, squat (SJ) and countermovement (CMJ) jumps, handgrip strength, and cardiorespiratory fitness.

RESULTS

We verified a correlation between PhA of the whole body and fat-free mass (r = 0.511), body mass index (r = 0.307), and body fat % (r = -0.303). There was a positive correlation between PhA of the whole body and SJ (r = 0.376), CMJ (r = 0.419), and handgrip for the dominant hand (r = 0.448). Moreover, PhA of the upper limbs was more strongly correlated with handgrip for the dominant (r = 0.630) and non-dominant hand (r = 0.575) compared to PhA of the whole body considering both sexes. Similarly, segmental PhA had a stronger significant correlation with SJ (r = 0.402) and handgrip for the dominant hand (r = 0.482) in males, as well as CMJ (r = 0.602) in females, compared to PhA of the whole body.

CONCLUSION

PhA of the whole body was positively related to fat-free mass, body mass index, body fat %, and lower- and upper-limbs strength in handball athletes. Segmental PhA might be used as a tool for estimating lower and upper limbs performance considering the sex, in preference to the PhA of the whole body.

Association between ACTN3 (R577X), ACE (I/D), BDKRB2 (-9/+9), and AGT (M268T) polymorphisms and performance phenotypes in Brazilian swimmers

BACKGROUND

The influence of genetic polymorphisms on athletic performance has been widely explored. This study investigated the interactions between the polymorphisms ACTN3 (R577X), ACE (I/D), BDKRB2 (-9/+9), and AGT (M/T) and their association with endurance and strength phenotypes in Brazilian swimmers.

METHODS

123 athletes (aged 20-30 years) and 718 controls participated in the study. The athletes were divided into elite and sub-elite (N = 19 and 104, respectively) and strength and endurance experts (N = 98 and 25, respectively). Hardy-Weinberg equilibrium was observed in all groups.

RESULTS

Considering the ACE polymorphism, it was observed a higher frequency of the DD genotype than expected in the strength experts of the elite group, whereas the strength experts sub-elite athletes had a higher frequency of the ID genotype (χ2 = 8.17; p = 0.01). Subjects with XX genotypes of ACTN3 are more likely to belong to the athlete group when compared to the control group (OR = 1.79, p = 0.04). The DD homozygotes of the ACE are more likely to belong to the elite group with strength phenotypes than the group of sub-elite (OR = 7.96, p = 0.01) and elite strength experts compared to elite endurance (OR = 18.0, p = 0.03). However, no significant differences were observed in the allelic distribution of the polymorphisms evaluated when comparing Elite, sub-elite athletes and controls.

CONCLUSION

ACE and ACTN3 allele frequencies should be considered with regard to performance influencing factors in Brazilian swimmers.

Impact of Menstrual cycle-based Periodized training on Aerobic performance, a Clinical Trial study protocol-the IMPACT study

BACKGROUND

The menstrual cycle and its impact on training and performance are of growing interest. However, evidence is lacking whether periodized exercise based on the menstrual cycle is beneficial. The primary purpose of this proposed randomized, controlled trial, the IMPACT study, is to evaluate the effect of exercise periodization during different phases of the menstrual cycle, i.e., comparing follicular phase-based and luteal phase-based training with regular training during the menstrual cycle on physical performance in well-trained women.

METHODS

Healthy, well-trained, eumenorrheic women between 18 and 35 years (n = 120) will be recruited and first assessed for physical performance during a run-in menstrual cycle at different cycle phases and then randomized to three different interventions: follicular phase-based training, luteal phase-based training, or regular training during three menstrual cycles. The training intervention will consist of high-intensity spinning classes followed by strength training. The menstrual cycle phases will be determined by serum hormone analysis throughout the intervention period. Assessment of aerobic performance (primary outcome) and muscle strength, body composition, and blood markers will be performed at baseline and at the end of the intervention.

DISCUSSION

With a robust methodology, this study has the potential to provide evidence of the differential effects of exercise periodization during different phases of the menstrual cycle in female athletes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05697263 . Registered on 25 January 2023.

Improvement of the aerobic performance in endurance athletes presenting nasal valve compromise with the application of an internal nasal dilator

PURPOSE

We investigated the effects of an internal nasal dilator on nasal airflow and cardio-respiratory capacity in adult endurance athletes, while performing controlled exhaustive physical exercise.

METHODS

Prospective observational study. Participants were 38 adult endurance athletes, 23 with and 15 without nasal valve compromise. Nasal patency was objectively evaluated with anterior rhinomanometry, acoustic rhinometry and peak nasal inspiratory flow (PNIF). Maximum oxygen uptake (VO2max), maximum pulmonary ventilation, time to exhaustion and total time of nasal respiration were recorded during a submaximal treadmill test. Dyspnea intensity and fatigue perception were evaluated using a labeled visual analog scale. All assessments were performed with and without the application of the internal nasal dilator.

RESULTS

All the parameters related to aerobic capacity were significantly reduced in the group of athletes with nasal valve compromise (p. <0.05 for all variables). The internal nasal dilator improved statistically significantly the nasal patency (p. <0.001), VO2max and aerobic performance and self-rating of dyspnea and fatigue (p. <0.05 for all parameters) only in athletes with nasal obstruction. PNIF correlated significantly with VO2max (rho = 0.4, p. <0.05).

CONCLUSIONS

Internal nasal dilation improves nasal patency and aerobic performance during submaximal exercise in adult endurance athletes with nasal obstruction symptoms due to nasal valve compromise.

Normative reference and cut-offs values of maximal aerobic speed-20 m shuttle run test and maximal oxygen uptake for Tunisian adolescent (elite) soccer players

This study aimed to develop reference curves of aerobic parameters of 20 m shuttle run test for Tunisian soccer players. The study was conducted in the 2022/2023 pre-season. The reference curves of the maximal aerobic speed (MAS) and the maximal oxygen uptake (VO2max) were developed according to the Lambda, Mu and Sigma (LMS) method, using data from 742 Tunisian premier league soccer players aged 11-18 years. Measured variables included: weight, height, body mass index and maximal heart rate (HRmax). HRmax was measured when the participants completed the maximal aerobic speed. VO2max was estimated using the 20 m shuttle run test protocol (speed increment every minute). Our results presented the smoothed percentiles (3rd, 10th, 25th, 50th, 75th, 90th and 97th) of MAS (km/h) and VO2max (ml/kg•min⁻1) according to age. In addition, raw data showed that VO2 max was positively correlated with age (r = 0.333; P < 0.001), height (cm) (r = 0.279; P < 0.001), weight (kg) (r = 0.266; P < 0.001), practice period (years) (r = 0.324; P < 0.001) and BMI (kg/m2) (r = 0.10; P < 0.05). However, it was negatively correlated to HRmax (bpm) (r = -0.247; P < 0.001). Only the measurements within the age group [12-12.99] are significantly higher (p < 0.001; ES = 0.63) compared with the previous age group [11-11.99]. Finally, regarding prevalence, our findings showed that 15.5 % of the players in our sample had VO2max values above the 87.7th percentile cut-off, while only 0.3 % exceeded the 99.18th percentile. The development of normative curves could help coaches and physical trainers to more accurately detect weaknesses in the aerobic performance of their players in order to sustain high-intensity repetitive actions during a soccer match.

Northern shrimp from multiple origins show similar sensitivity to global change drivers, but different cellular energetic capacity

Species with a wide distribution can experience significant regional variation in environmental conditions, to which they can acclimatize or adapt. Consequently, the geographic origin of an organism can influence its responses to environmental changes, and therefore its sensitivity to combined global change drivers. This study aimed at determining the physiological responses of the northern shrimp, Pandalus borealis, at different levels of biological organization and from four different geographic origins, exposed to elevated temperature and low pH to define its sensitivity to future ocean warming and acidification. Shrimp sampled within the northwest Atlantic were exposed for 30 days to combinations of three temperature (2, 6 or 10°C) and two pH levels (7.75 or 7.40). Survival, metabolic rates, whole-organism aerobic performance and cellular energetic capacity were assessed at the end of the exposure. Our results show that shrimp survival was negatively affected by temperature above 6°C and low pH, regardless of their origin. Additionally, shrimp from different origins show overall similar whole-organism performances: aerobic scope increasing with increasing temperature and decreasing with decreasing pH. Finally, the stability of aerobic metabolism appears to be related to cellular adjustments specific to shrimp origin. Our results show that the level of intraspecific variation differs among levels of biological organization: different cellular capacities lead to similar individual performances. Thus, the sensitivity of the northern shrimp to ocean warming and acidification is overall comparable among origins. Nonetheless, shrimp vulnerability to predicted global change scenarios for 2100 could differ among origins owing to different regional environmental conditions.

Altitude acclimatization, hemoglobin-oxygen affinity, and circulatory oxygen transport in hypoxia

In mammals and other air-breathing vertebrates that live at high altitude, adjustments in convective O₂ transport via changes in blood hemoglobin (Hb) content and/or Hb-O₂ affinity can potentially mitigate the effects of arterial hypoxemia. However, there are conflicting views about the optimal values of such traits in hypoxia, partly due to the intriguing observation that hypoxia-induced acclimatization responses in humans and other predominantly lowland mammals are frequently not aligned in the same direction as evolved phenotypic changes in high-altitude natives. Here we review relevant theoretical and empirical results and we highlight experimental studies of rodents and humans that provide insights into the combination of hematological changes that help attenuate the decline in aerobic performance in hypoxia. For a given severity of hypoxia, experimental results suggest that optimal values for hematological traits are conditional on the states of other interrelated phenotypes that govern different steps in the O₂-transport pathway.

The efficacy of weekly and bi-weekly heat training to maintain the physiological benefits of heat acclimation

OBJECTIVES

To examine the efficacy of weekly and bi-weekly heat training to maintain heat acclimatization (HAz) and heat acclimation (HA) for 8 weeks in aerobically trained athletes.

DESIGN

Randomized, between-group.

METHODS

Twenty-four males (mean [m ± standard deviation [sd]; (age, 34 ± 12 y; body mass, 72.6 ± 8.8 kg, VO_2peak, 57.7 ± 6.8 mL·kg^-1·min^-1) completed five trials (baseline, following HAz, following HA (HAz + HA), four weeks into heat training [HT_WK4], and eight weeks into HT [HT_WK8] that involved 60 min of steady-state exercise (59.1 ± 1.8% vVO_2peak) in an environmental laboratory (wet bulb globe temperature [WBGT], 29.6 ± 1.4 °C) on a motorized treadmill. Throughout exercise, heart rate (HR) and rectal temperature (T_rec) were recorded. Following HAz + HA, participants were assigned to three groups: control group (HT₀), once per week heat training (HT₁), and twice per week heat training (HT₂). HT involved heated exercise (WBGT, 33.3 ± 1.3 °C) to achieve hyperthermia (38.5-39.75 °C) for 60 min. Repeated measures ANOVAs were used to determine differences.

RESULTS

HAz + HA resulted in significant improvements in HR (p < 0.001) and T_rec (p < 0.001). At HT_WK8, HR was significantly higher in HT₀ (174 ± 22 beats⋅min^-1) compared to HT₂ (151 ± 17 beats⋅min^-1, p < 0.023), but was not different than HT₁ (159 ± 17 beats⋅min^-1, p = 0.112). There was no difference in % change of T_rec from post-HAz + HA to HT_WK4 (0.6 ± 1.3%; p = 0.218), however, HT_WK8 (1.8 ± 1.4%) was significantly greater than post-HAz + HA in HT₀ (p = 0.009).

CONCLUSIONS

Bi-weekly HT provided clear evidence for the ability to maintain physiological adaptions for 8 weeks following HA.

Commentary: Hierarchical reductionism approach to understanding adaptive variation in animal performance

Aerobic capacity is a complex performance trait with important consequences for fitness, and is determined by the integrated function of the O₂ transport pathway. The components of the O₂ pathway interact and function as an integrated physiological system, which could strongly influence the contribution of each component to variation in aerobic capacity. In this commentary, we highlight the value of hierarchical reductionism - combining studies of how component parts work in isolation with studies of how components interact within integrated systems - for understanding the evolution of aerobic capacity. This is achieved by focussing on the role of haemoglobin in adaptive increases in aerobic capacity in high-altitude deer mice (Peromyscus maniculatus). High-altitude deer mice have evolved increased aerobic capacity in hypoxia, in association with evolved changes in several subordinate traits across the O₂ pathway. This includes an evolved increase in Hb-O₂ affinity - which helps safeguard arterial O₂ saturation in hypoxia - and reductionist approaches have been successful at identifying the genetic, structural, and biochemical underpinnings of variation in this trait. However, theoretical modelling and empirical measurements suggest that increased Hb-O₂ affinity may not augment aerobic capacity on its own. The adaptive benefit of increased Hb-O₂ affinity in high-altitude deer mice appears to have been contingent upon antecedent changes in other traits in the O₂ pathway, particularly an increased capacity for O₂ diffusion and utilization in active tissues. These findings highlight the importance of understanding the interactions between the components of integrated systems for fully appreciating the evolution of complex performance phenotypes.

Influence of post-exercise hot-water therapy on adaptations to training over 4 weeks in elite short-track speed skaters

This study aimed to investigate the effects of regular hot water bathing (HWB), undertaken 10 min after the last training session of the day, on chronic adaptations to training in elite athletes. Six short-track (ST) speed skaters completed four weeks of post-training HWB and four weeks of post-training passive recovery (PR) according to a randomized cross-over study. During HWB, participants sat in a jacuzzi (40 °C; 20 min). According to linear mixed models, maximal isometric strength of knee extensor muscles was significantly increased for training with HWB (p < 0.0001; d = 0.41) and a tendency (p = 0.0529) was observed concerning V˙O2max. No significant effect of training with PR or HWB was observed for several variables (p > 0.05), including aerobic peak power output, the decline rate of jump height during 1 min-continuous maximal countermovement jumps (i.e. anaerobic capacity index), and the force-velocity relationship. Regarding specific tasks on ice, a small effect of training was found on both half-lap time and total time during a 1.5-lap all-out exercise (p = 0.0487; d = 0.23 and p = 0.0332; d = 0.21, respectively) but no additional effect of HWB was observed. In summary, the regular HWB protocol used in this study can induce additional effects on maximal isometric strength without compromising aerobic and anaerobic adaptations or field performance in these athletes.

Combined effects of solar radiation and airflow on endurance exercise capacity in the heat

This study investigated the combined effects of different levels of solar radiation and airflow on endurance exercise capacity and thermoregulatory responses during exercise-heat stress. Ten males cycled at 70% peak oxygen uptake until exhaustion in an environmental chamber (30°C, 50% relative humidity). Four combinations of solar radiation and airflow were tested (800 W⋅m^-2 and 10 km⋅h^-1 [High-Low], 800 W⋅m^-2 and 25 km⋅h^-1 [High-High], 0 W⋅m^-2 and 10 km⋅h^-1 [No-Low], and 0 W⋅m^-2 and 25 km⋅h^-1 [No-High]). Participants were exposed to solar radiation by a ceiling-mounted solar simulator (Metal halide lamps) and the headwind by two industrial fans. Time to exhaustion was shorter (p < 0.05) in High-Low (mean ± SD; 35 ± 7 min) than the other trials and in High-High (43 ± 6 min) and No-Low (46 ± 9 min) than No-High (61 ± 9 min). There was an interaction effect in total (dry + evaporative) heat exchange which was less in High-Low and High-High than No-Low and No-High, and in No-Low than No-High (all p < 0.001). Core temperature, heart rate and thermal sensation were higher in high (High-Low and High-High) than no (No-Low and No-High) solar radiation trials and in lower (High-Low and No-Low) than higher (High-High and No-High) airflow trials (p < 0.05). Mean skin temperature and rating of perceived exertion were higher in high than no solar radiation trials (p < 0.05). This study indicates that combining high solar radiation and lower airflow have negative effects on thermoregulatory and perceptual strain and endurance exercise capacity than when combining high solar radiation and higher airflow and combining no solar radiation and lower/higher airflow during exercise-heat stress.

Is a verification phase needed to determine [Formula: see text]O2max across fitness levels?

INTRODUCTION

Current methods (plateau/secondary criteria) to determine maximal oxygen consumption ([Formula: see text]O_2max) are inconsistently achieved leading some to suggest the use of a verification phase (VP) to confirm [Formula: see text]O_2max.

PURPOSE

To provide further evidence for the inclusion of a VP to confirm [Formula: see text]O_2max in different fitness levels.

METHODS

Forty-nine participants (22 females; 21.9 ± 2.6 years, 24.3 ± 2.8 kg m^-2, 45.27 ± 7.68 mL kg^-1 min^-1) had their [Formula: see text]O₂ and heart rate measured during three graded exercise tests (GXT) on separate days each followed by a VP of differing intensity (85%, 95%, 105% final workload). Participants were divided into groups using norms adapted from American College of Sports Medicine [Formula: see text]O_2max guidelines (30.47-61.47 mL kg^-1 min^-1). [Formula: see text]O_2max was confirmed if the [Formula: see text]O_2peak on the VP or an additional GXT was within ± 2 × typical error of the [Formula: see text]O_2peak attained on the first GXT. There was no effect of test number so the third GXT was not included in comparison with VP.

RESULTS

The [Formula: see text]O_2peak from the first GXT was not different than either value attained following the VP at 95 or 105% workload or a second GXT (p > 0.999). The 85% VP [Formula: see text]O_2peak was lower than the first GXT [Formula: see text]O_2peak (p = 0.002). The VP confirmed the GXT [Formula: see text]O_2peak on 73% of VP (no differences among fitness levels). Submaximal VP (85 and 95%) was less effective as 65% and 51% of participants achieved a higher [Formula: see text]O_2peak on one of the GXT.

CONCLUSION

The use of a VP at 105% or a second GXT was able to confirm the [Formula: see text]O_2max value attained across a range of fitness levels.

Dietary and plasma blood α-linolenic acid as modulators of fat oxidation and predictors of aerobic performance

Background

Among n-3 polyunsaturated fatty acids (PUFAs), the most important is α-linolenic acid (ALA). The biological activity of ALA is not equivalent to that of the long-chain n-3 PUFAs, and it has pleiotropic effects, such as functioning as an energy substrate during long-term training when carbohydrate reserves are depleted. The purpose of this investigation was to study the link between the essential dietary and plasma ALA and aerobic performance, which is estimated via maximal fat oxidation (MFO), among skiers.

Methods

Twenty-four highly trained male athletes from the Russian cross-country skiing team participated in the study. ALA intake was determined by an original program used to assess the actual amount and frequency of fat consumption. The plasma level of ALA was determined using gas-liquid chromatography. The skiers’ aerobic performance was estimated via MFO and determined by indirect calorimetry using the system “Oxycon Pro”.

Results

The consumption of ALA in the diet in half of the skiers was below the recommended level at 0.5 ± 0.2 g/day. The deficiency of plasma ALA levels was on average 0.2 ± 0.1 Mol% for almost all participants. The consumption of ALA in the diet and its level in plasma were associated with MFO (r_s = 0.507, p = 0.011; r_s = 0.460, p = 0.023). Levels of ALA in plasma (p = 0.0523) and the consumption of ALA in the diet (p = 0.0039) were associated with high aerobic performance.

Conclusions

ALA in the diet of the athletes may be used as nutritional support to increase MFO and aerobic performance.

Effects of Concurrent Training and a Multi-Ingredient Performance Supplement Containing Rhodiola rosea and Cordyceps sinensis on Body Composition, Performance, and Health in Active Men

INTRODUCTION

Supplementation with Rhodiola Rosea (RR) and Cordyceps Sinensis (CS) has been shown to improve aerobic performance, but their influence on concurrent training (resistance training plus high intensity interval training) outcomes has not been established. The purpose of this study was to determine the effects of supplementation with a multi-ingredient performance supplement (MIPS) containing RR and CS during a 14-week training and testing program on body composition, weekly exercise training outcomes, overall training and performance outcomes, and hormone profiles.

METHODS

Active college-aged men (N = 21) were stratified into either a MIPS or a placebo (PLA) group. Both groups completed 14 weeks of training and testing. Body composition, overall training outcomes, and blood sample collection occurred at weeks 0, 7, and 14, while training performance was evaluated weekly.

RESULTS

Both groups improved (p < 0.05) percent body fat (-1.3%), bench press (+4%) and squat strength (+8%), with no difference between groups. Serum cortisol concentrations significantly decreased (-11%) but there were no differences between groups. No other changes in blood hormone profiles occurred. Weekly exercise performance data suggests that MIPS improved sprint performance, bench press lifting volume, and total workload, but this did not lead to improved overall training performance compared to PLA over the14-week study.

CONCLUSION

Despite MIPS improving certain aspects of weekly training performance, supplementation with MIPS for 14 weeks did not improve body composition, overall training and performance outcomes, or blood biomarkers of health in response to concurrent training in young men compared to PLA. This study was registered with clinicaltrials. gov (NCT02383017).

Effect of skill-based training vs. small-sided games on physical performance improvement in young soccer players

Recently, there has been increasing attention to research related to the effect of skill-based or game-based training on soccer players’ physical performance. Therefore, this study aimed to compare the effectiveness of skill-based training (SBT) at maximum intensity versus the small-sided game (SSG) on the physical performance characteristics of young soccer players during the pre-season period. Twenty-two male soccer players (mean age 15.3 ± 3 years) were randomly assigned to either an SBT or SSG fully controlled intervention programme, running parallel for eight weeks and held twice a week. On three non-consecutive days before and after training players completed a test battery consisting of the 20 m sprint, T-run, countermovement jump, running anaerobic sprint test (RAST) and 20 m shuttle run. Data were analysed with a two-way ANOVA test for repeated measures. SBT and SSG interventions induced a significant improvement in the anaerobic power (10.9% vs 6.2%), explosive power (8.5% vs 5.6%), VO2max (6.7% vs 6.5%) and vertical jump (5.3% vs 2.9%), respectively. When the improvements in the physical performance variables of both groups are compared, the SBT group achieved greater improvement than the SSG group in anaerobic power (by 4.7%), in explosive power (by 2.8%), in vertical jumping (by 2.3%), in the 20 m sprint (by 2.2%) and T-test scores (by 1.7%). However, improvements in the VO2max were similar in both groups. The results of the present study suggest that SBT at maximum intensity may be more effective than SSG in improving the physical performance characteristics of young soccer players in the pre-competitive season.

Twelve Weeks of Aerobic Exercise at the Lactate Threshold Improves Autonomic Nervous System Function, Body Composition, and Aerobic Performance in Women with Obesity

Background

The present study examined the effects of a prolonged exercise intervention at the lactate threshold (LT) on body composition, aerobic performance, and the autonomic nervous system (ANS) in women with obesity.

Methods

A total of 36 obese Korean women aged 36 to 55 years (mean±standard deviation, 44.8±5.2 years) were randomly assigned to a control group (CON, n=18) or an experimental group (EXP, n=18); and EXP underwent aerobic exercise training three times a week at a heart rate corresponding to the LT (HR_LT) for 12 weeks. All dependent variables (body composition, aerobic performance, and ANS function parameters) were evaluated before and after training.

Results

Compared with the CON group, the EXP group showed significant improvement in body composition (body weight, -4.57 vs. -2.40 kg; body mass index, -1.79 vs. -0.96 kg/m²; %body fat, -4.63 vs. -1.41; fat-free mass, 3.24 vs. -0.08 kg), aerobic performance (oxygen consumption at LT, 5.74 vs. 0.12 mL/kg/min; maximal oxygen consumption, 5.41 vs. 2.14 mL/kg/min; treadmill speed at HR_LT, 1.40 vs. 0.29 km/hr; bicycle load at HR_LT, 18.62 vs. 4.52 w; and ANS function (mean RR, 50.83 vs. -15.04 ms; standard deviation of NN intervals, 5.08 vs. -0.55 ms; root mean square of successive differences, 6.42 vs. 1.87 ms; total power, 0.34 vs. 0.10 ms²; high frequency, 0.32 vs. -0.04 ms²; low frequency/high frequency, -0.09 vs. 0.01).

Conclusion

Aerobic exercise at the LT for 12 weeks is a practical method of improving body composition, aerobic performance, and ANS function for women with obesity.

High-intensity interval versus moderate-intensity continuous half-marathon training programme for middle-aged women

PURPOSE

To test the effectiveness on recreational female middle-aged runners of a programme of high-intensity interval training (HIIT) for a half-marathon race contrasted to a conventional moderate-intensity continuous training (MICT).

METHODS

Twenty recreational female runners (40 ± 7 years) followed MICT or HIIT schedules for training a half-marathon. The MICT group trained a mean of 32 km/week at intensities below 80% VO₂max. The HIIT group ran 25 km/week at intensities between 80 and 100% VO₂max, combined with uphill running and resistance training. Women following HIIT ran 21% less distance and invested 17% less time than those from MICT group. All the women were evaluated at the beginning and end of the training and participated in the same half-marathon run.

RESULTS

Women following both schedules reduced their previous finishing times by 2-3%, which for HIIT group would have meant rising up to 90 positions out of 1454 participants in the local half-marathon race. The high intensity performed during series of high power output (200 m and 400 m) and resistance sessions in HIIT programme promoted changes that allowed modifying efficiency at high workloads. At the same time, the HIIT training programme elicited changes in oxygen uptake and transport as indicated the cardiorespiratory parameters obtained during recovery in lab tests. Moreover, HIIT registered a 14% baseline decrease in heart rate contrasting to the not significant 6% decrease in MICT.

CONCLUSIONS

Runners following HIIT training obtained similar registers as with a traditional MICT schedule, expending less time and running shorter distances, yet improving their anaerobic and aerobic power.

Stress coping and evolution of aerobic exercise performance: corticosterone levels in voles from a selection experiment

The locomotor performance achieved in a challenging situation depends not only on physiological limitations, such as the aerobic exercise capacity, but also on behavioral characteristics, such as adequate coping with stress. The stress response is mediated largely by the hypothalamic-pituitary-adrenal (HPA) axis, through modulated release of glucocorticoids. We used a unique experimental evolution model system to test the hypothesis that the evolution of an increased aerobic exercise performance can be facilitated by modification of the glucocorticoid-related stress-coping mechanisms. Bank voles (Myodes glareolus) from 'aerobic' (A) lines, selected for 22 generations for high maximum swim-induced rate of oxygen consumption (V̇ _O2,swim), achieved a 64% higher V̇ _O2,swim than those from unselected, control lines. The temporal pattern of exercise during the swimming trial also evolved, and the A-line voles achieved V̇ _O2,swim later in the course of the trial, which indicates a modification of the stress response characteristics. Both V̇ _O2,swim and the average metabolic rate measured during the trial tended to increase with baseline corticosterone level, and decreased with the post-exercise corticosterone level. Thus, increased baseline corticosterone level promotes high metabolic performance, but a high corticosterone response to swimming acts as an inhibitor rather than stimulator of intense activity. However, neither of the corticosterone traits differed between the A-selected and control lines. Thus, the experiment did not provide evidence that evolution of increased aerobic performance is facilitated by the modification of glucocorticoid levels. The results, however, do not exclude the possibility that other aspects of the HPA axis function evolved in response to the selection.

No ergogenic effects of a 10-day combined heat and hypoxic acclimation on aerobic performance in normoxic thermoneutral or hot conditions

PURPOSE

Hypoxic acclimation enhances convective oxygen delivery to the muscles. Heat acclimation-elicited thermoregulatory benefits have been suggested not to be negated by adding daily exposure to hypoxia. Whether concomitant acclimation to both heat and hypoxia offers a synergistic enhancement of aerobic performance in thermoneutral or hot conditions remains unresolved.

METHODS

Eight young males ([Formula: see text]: 51.6 ± 4.6 mL min^-1 kg^-1) underwent a 10-day normobaric hypoxic confinement (F_iO₂ = 0.14) interspersed with daily 90-min normoxic controlled hyperthermia (target rectal temperature: 38.5 °C) exercise sessions. Prior to, and following the confinement, the participants conducted a 30-min steady-state exercise followed by incremental exercise to exhaustion on a cycle ergometer in thermoneutral normoxic (NOR), thermoneutral hypoxic (F_iO₂ = 0.14; HYP) and hot (35 °C, 50% relative humidity; HE) conditions in a randomized and counterbalanced order. The steady-state exercise was performed at 40% NOR peak power output (W_peak) to evaluate thermoregulatory function. Blood samples were obtained from an antecubital vein before, on days 1 and 10, and the first day post-acclimation.

RESULTS

[Formula: see text] and ventilatory thresholds were not modified in any environment following acclimation. W_peak increased by 6.3 ± 3.4% in NOR and 4.0 ± 4.9% in HE, respectively. The magnitude and gain of the forehead sweating response were augmented in HE post-acclimation. EPO increased from baseline (17.8 ± 7.0 mIU mL^-1) by 10.7 ± 8.8 mIU mL^-1 on day 1 but returned to baseline levels by day 10 (15.7 ± 5.9 mIU mL^-1).

DISCUSSION

A 10-day combined heat and hypoxic acclimation conferred only minor benefits in aerobic performance and thermoregulation in thermoneutral or hot conditions. Thus, adoption of such a protocol does not seem warranted.

Effects of hypoxia on swimming and sensing in a weakly electric fish

Low dissolved oxygen (hypoxia) can severely limit fish performance, especially aerobically expensive behaviours including swimming and acquisition of sensory information. Fishes can reduce oxygen requirements by altering these behaviours under hypoxia, but the underlying mechanisms can be difficult to quantify. We used a weakly electric fish as a model system to explore potential effects of hypoxia on swim performance and sensory information acquisition, which enabled us to non-invasively record electric signalling activity used for active acquisition of sensory information during swimming. To quantify potential effects of hypoxia, we measured critical swim speed (U_crit) and concurrent electric signalling activity under high- and low-dissolved oxygen concentrations in a hypoxia-tolerant African mormyrid fish, Marcusenius victoriae Fish were maintained under normoxia for 6 months prior to experimental treatments, and then acclimated for 8 weeks to normoxia or hypoxia and tested under both conditions (acute: 4 h exposure). Acute hypoxia exposure resulted in a significant reduction in both U_crit and electric signalling activity in fish not acclimated to hypoxia. However, individuals acclimated to chronic hypoxia were characterized by a higher U_crit under both hypoxia and normoxia than fish acclimated to normoxia. Following a 6 month re-introduction to normoxia, hypoxia-acclimated individuals still showed increased performance under acute hypoxic test conditions, but not under normoxia. Our results highlight the detrimental effects of hypoxia on aerobic swim performance and sensory information acquisition, and the ability of fish to heighten aerobic performance through acclimation processes that can still influence performance even months after initial exposure.

Effect of wrist cooling on aerobic and anaerobic performance in elite sportsmen

BACKGROUND

Body cooling has been used to increase sporting performance and enhance recovery. Several studies have reported improvement in exercise capacities using forearm and hand cooling or only hand cooling. Wrist cooling has emerged as a portable light weight solution for precooling prior to sporting activity. The Astrand test for aerobic performance and the Wingate test for anaerobic performance are reliable and accurate tests for performance assessment. This study conducted on elite Indian athletes analyses the effects of wrist precooling on aerobic and anaerobic performance as tested by the Astrand test and the Wingate test before and after wrist precooling.

METHODS

67 elite sportsmen were administered Wingate and Astrand test under standardised conditions with and without wrist precooling using a wrist cooling device (dhamaSPORT). Paired t-test was applied to study effect on aerobic [VO2 (ml/min/kg)] and anaerobic performance [peak power (W/kg) and average power (W/kg)] and Cohen's d was used to calculate effect size of wrist precooling.

RESULTS

After wrist precooling, significant increase of 0.22 (p = 0.014, 95% CI: 0.047, 0.398) in peak power (W/kg) and 0.22 (p < 0.0001, 95% CI: 0.142, 0.291) was observed in average power (W/kg). Although, an increase of 1.38 (p = 0.097, 95% CI: -0.225, 3.012) was observed in VO2 (ml/min/kg), wrist precooling was not significantly effective in aerobic performance. Wrist cooling effect size was smaller in VO2 (Cohen's d = 0.21), peak power (Cohen's d = 0.31) and it was larger in average power (Cohen's d = 0.71).

CONCLUSION

Results show wrist precooling significantly improves anaerobic than aerobic performance of elite sportsmen.

Ocean acidification narrows the acute thermal and salinity tolerance of the Sydney rock oyster Saccostrea glomerata

Coastal and estuarine environments are characterised by acute changes in temperature and salinity. Organisms living within these environments are adapted to withstand such changes, yet near-future ocean acidification (OA) may challenge their physiological capacity to respond. We tested the impact of CO₂-induced OA on the acute thermal and salinity tolerance, energy metabolism and acid-base regulation capacity of the oyster Saccostrea glomerata. Adult S. glomerata were acclimated to three CO₂ levels (ambient 380μatm, moderate 856μatm, high 1500μatm) for 5weeks (24°C, salinity 34.6) before being exposed to a series of acute temperature (15-33°C) and salinity (34.2-20) treatments. Oysters acclimated to elevated CO₂ showed a significant metabolic depression and extracellular acidosis with acute exposure to elevated temperature and reduced salinity, especially at the highest CO₂ of 1500μatm. Our results suggest that the acute thermal and salinity tolerance of S. glomerata and thus its distribution will reduce as OA continues to worsen.

Circulatory mechanisms underlying adaptive increases in thermogenic capacity in high-altitude deer mice

We examined the circulatory mechanisms underlying adaptive increases in thermogenic capacity in deer mice (Peromyscus maniculatus) native to the cold hypoxic environment at high altitudes. Deer mice from high- and low-altitude populations were born and raised in captivity to adulthood, and then acclimated to normoxia or hypobaric hypoxia (simulating hypoxia at ∼4300 m). Thermogenic capacity [maximal O₂ consumption (V̇_O2,max), during cold exposure] was measured in hypoxia, along with arterial O₂ saturation (Sa_O2 ) and heart rate (f_H). Hypoxia acclimation increased V̇_O2,max by a greater magnitude in highlanders than in lowlanders. Highlanders also had higher Sa_O2  and extracted more O₂ from the blood per heartbeat (O₂ pulse=V̇_O2,max/f_H). Hypoxia acclimation increased f_H, O₂ pulse and capillary density in the left ventricle of the heart. Our results suggest that adaptive increases in thermogenic capacity involve integrated functional changes across the O₂ cascade that augment O₂ circulation and extraction from the blood.

Is cardiorespiratory fitness impaired in PCOS women? A review of the literature

PURPOSE

Polycystic ovary syndrome (PCOS) is a common and heterogeneous endocrine disorder, affecting 8-12% of reproductive-aged women. Insulin resistance and body fat excess are common features in these subjects. Increased physical activity and diet modifications are the first recommended approach in the management of these women, at least in overweight/obese subjects. Evaluation of cardiorespiratory fitness (CRF) is important in assessing exercise performance and in monitoring the effects of physical exercise interventions. Several studies have shown that CRF may be impaired in metabolic and endocrine disorders. However, there are little data on this issue in PCOS women. The aim of this narrative review is to critically evaluate whether aerobic capacity is altered in PCOS women, focusing on maximal oxygen uptake.

METHODS

An updated search of the literature was performed, identifying papers with maximal oxygen consumption measurements in women with PCOS compared to healthy controls.

RESULTS

We have identified six studies on this specific topic: four of them showed an alteration of maximal oxygen consumption in PCOS women, whereas two did not. However, taken together these studies suggest that CRF may be strikingly impaired in both normal-weight and overweight/obese subjects with this condition.

CONCLUSIONS

Women with PCOS appear to be characterized by a reduced cardiopulmonary fitness. However, further research on this topic is needed. This information may hopefully help clinicians and exercise specialist in planning individualized exercise programs aimed at improving the metabolic and endocrine outcomes in these women.

Subchronic exposure to chlorpyrifos affects energy expenditure and detoxification capacity in juvenile Japanese quails

Effects of pesticides on non-target organisms have been studied in several taxa at different levels of biological organization, from enzymatic to behavioral responses. Although the physiological responses may be associated with higher energy costs, little is known about metabolic costs of pesticide detoxification in birds. To fill this gap, we exposed orally (diet) 15-d old Coturnix coturnix japonica individuals to sublethal doses of chlorpyrifos (10 and 20 mg active ingredient/kg dry food) for four weeks. Carboxylesterase (CbE), butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) activities were periodically measured in multiple tissues along with measurements of resting (RMR) and maximum metabolic rates (M(sum)). Furthermore, glucuronic acid in bird excreta was also assessed at the end of the trial. While CbE and BChE activities were inhibited by chlorpyrifos in all tissues during the third and fourth weeks following pesticide treatment, AChE activity was unaffected. At this sampling times, both M(sum) and RMR expansibility decreased. These results suggest that the exposure to chlorpyrifos caused a negative effect on aerobic performance. Additionally, excretion rate of glucuronic acid was up to 2-fold higher in the 20-mg/kg group than in the control and 10-mg/kg chlorpyrifos groups. The inhibition of CbE and BChE activities corroborated that these enzymes are fulfilling their role as bioscavengers for organophosphate pesticides, decreasing its concentration and thus protecting AChE activity against inhibition by chlorpyrifos.

A randomized trial of coenzyme Q10 in patients with confirmed statin myopathy

BACKGROUND

Coenzyme Q10 (CoQ10) supplementation is the most popular therapy for statin myalgia among both physicians and patients despite limited and conflicting evidence of its efficacy.

OBJECTIVE

This study examined the effect of coenzyme Q10 (CoQ10) supplementation on simvastatin-associated muscle pain, muscle strength and aerobic performance in patients with confirmed statin myalgia.

METHODS

Statin myalgia was confirmed in 120 patients with prior symptoms of statin myalgia using an 8-week randomized, double-blind crossover trial of simvastatin 20 mg/d and placebo. Forty-one subjects developed muscle pain with simvastatin but not with placebo and were randomized to simvastatin 20 mg/d combined with CoQ10 (600 mg/d ubiquinol) or placebo for 8 weeks. Muscle pain (Brief Pain Inventory [BPI]), time to pain onset, arm and leg muscle strength, and maximal oxygen uptake (VO2max) were measured before and after each treatment.

RESULTS

Serum CoQ10 increased from 1.3 ± 0.4 to 5.2 ± 2.3 mcg/mL with simvastatin and CoQ10, but did not increase with simvastatin and placebo (1.3 ± 0.3 to 0.8 ± 0.2) (p < 0.05). BPI pain severity and interference scores increased with simvastatin therapy (both p < 0.01), irrespective of CoQ10 assignment (p = 0.53 and 0.56). There were no changes in muscle strength or VO2max with simvastatin with or without CoQ10 (all p > 0.10). Marginally more subjects reported pain with CoQ10 (14 of 20 vs 7 of 18; p = 0.05). There was no difference in time to pain onset in the CoQ10 (3.0 ± 2.0 weeks) vs. placebo (2.4 ± 2.1 wks) groups (p = 0.55). A similar lack of CoQ10 effect was observed in 24 subjects who were then crossed over to the alternative treatment.

CONCLUSIONS

Only 36% of patients complaining of statin myalgia develop symptoms during a randomized, double-blind crossover of statin vs placebo. CoQ10 supplementation does not reduce muscle pain in patients with statin myalgia. Trial RegistrationNCT01140308; www.clinicaltrials.gov.

The relationship between cardiopulmonary size and aerobic performance in adult deer mice at high altitude

Deer mice (Peromyscus maniculatus sonoriensis) populations in the White Mountains of Eastern California are found across a substantial range of partial pressures of oxygen (PO₂). Reduction in PO₂ at high altitude can have a negative impact on aerobic performance. We studied plastic changes in organ mass and volume involved in aerobic respiration in response to acclimation to high altitude, and how those changes are matched with aerobic performance measured by VO₂,max. Adult deer mice born and raised at 340 m were acclimated at either 340 or 3800 m for a period of 9 weeks. Lung volume increased by 9% in mice acclimated to high altitude. VO₂,max was also significantly higher under hypoxic conditions after high altitude acclimation compared with controls. Body mass-corrected residuals of VO₂,max were significantly correlated with an index of cardiopulmonary size (summed standardized residuals of lung volume and heart mass) under both hypoxic and normoxic conditions. These data show that phenotypic plasticity in lung volume and heart mass plays an important role in maintaining aerobic performance under hypoxic conditions, and accounts for up to 55% of the variance in aerobic performance.

Maximal oxygen consumption and bone mineral density in a group of young Lebanese adults

The aim of this study was to explore the relationship between maximal oxygen consumption (VO2 max) and bone mineral density (BMD) in a group of young Lebanese adults. Twenty women and 37 men whose ages range from 18 to 32 yr participated in this study. Informed written consent was obtained from the participants. Body weight and height were measured, and body mass index was calculated. VO2 max was determined by direct measurement while exercising on a bicycle ergometer (Siemens-Elema RE 820; Rodby Elektronik AB, Enhorna, Sweden). Whole body bone mineral content (WB BMC), whole body bone mineral density (WB BMD), lumbar spine BMD (L1-L4 BMD), total hip BMD (TH BMD), and femoral neck BMD (FN BMD) were measured by dual-energy X-ray absorptiometry. In women, VO2 max (expressed as L/mn) was positively correlated to WB BMC (r = 0.82; p < 0.001), WB BMD (r = 0.80; p < 0.001), L1-L4 BMD (r = 0.73; p < 0.001), TH BMD (r = 0.80; p < 0.001), and FN BMD (r = 0.85; p < 0.001). In men, VO2 max (expressed as L/mn) was positively correlated to WB BMC (r = 0.57; p < 0.001), WB BMD (r = 0.53; p < 0.001), L1-L4 BMD (r = 0.50; p < 0.001), TH BMD (r = 0.38; p < 0.01), and FN BMD (r = 0.30; p < 0.05). In both sexes, the positive associations between VO2 max and bone variables (BMC and BMD) remained significant after adjustment for age (p < 0.001). This study suggests that VO2 max (L/mn) is a positive determinant of BMC and BMD in young adults. Aerobic power seems to be a determinant of BMC and BMD in young adults.

Surgical resection of primary tumour improves aerobic performance in colorectal cancer

BACKGROUND

Colorectal cancer is the third most common cancer in the UK, with patients suffering declines in muscle mass and aerobic function. We hypothesised that tumour removal in non-metastatic colorectal cancer would lead to a restoration of lean muscle mass and increases in objective and subjective measures of aerobic performance.

METHODS

We recruited two groups: patients with colorectal cancer (n = 30, 65.3 (51-77) y, body mass index 27.67 (4.83) kg m(-2)) and matched controls (n = 30, 64.6 (42-77) y, BMI 27.14 (3.51) kg m(-2)). Controls underwent a single study while colorectal cancer patients were studied before and 10 months after tumour resection. Aerobic performance was assessed via cardiopulmonary exercise testing and activity questionnaires. Lean muscle mass was measured via dual-energy X-ray absorptiometry.

RESULTS

Lean muscle mass was not different between groups (control: 47.82 (8.23); pre-resection: 52.41 (10.59); post-resection: 52.38 (10.52), kg). Anaerobic threshold was lower in pre-operative patients compared to controls (14.40 (3.23) vs. 19.67 (5.81) ml kg(-1) min(-1), p < 0.0001), increasing significantly post-resection (17.00 (3.56) ml kg(-1) min(-1)p < 0.0001). Self reported maximal physical activity was lower after resection compared to preoperatively (pre-resection 6.0 (6.5-5 IQR), post-resection 3.75 (4-3 IQR), p < 0.0001).

CONCLUSION

In colorectal cancer, anaerobic threshold is reached more rapidly than in matched controls, returning toward normal with tumour resection. Self-reported measures of activity do not mirror this objective change, cardiopulmonary exercise testing may therefore allow for a more accurate evaluation of pre and postoperative performance capability. The variance between objective and subjective measures of exercise capacity may be important in determining return to normal activities.