Endurance Exercise Sessions Research Articles

Acute Aerobic Exercise Remodels the Adipose Tissue Progenitor Cell Phenotype in Obese Adults.

Adipose tissue pathology in obese patients often features impaired adipogenesis, angiogenesis, and chronic low-grade inflammation, all of which are regulated in large part by adipose tissue stromal vascular cells [SVC; i.e., non-adipocyte cells within adipose tissue including preadipocytes, endothelial cells (ECs), and immune cells]. Exercise is known to increase subcutaneous adipose tissue lipolysis, but the impact of exercise on SVCs in adipose tissue has not been explored. The purpose of this study was to assess the effects of a session of exercise on preadipocyte, EC, macrophage, and T cell content in human subcutaneous adipose tissue. We collected abdominal subcutaneous adipose tissue samples from 10 obese adults (BMI 33 ± 3 kg/m2, body fat 41 ± 7%) 12 h after a 60 min acute session of endurance exercise (80 ± 3%HRpeak) vs. no acute exercise session. SVCs were isolated by collagenase digestion and stained for flow cytometry. We found that acute exercise reduced preadipocyte content (38 ± 7 vs. 30 ± 13%SVC; p = 0.04). The reduction was driven by a decrease in CD34hi preadipocytes (18 ± 5 vs. 13 ± 6%SVC; p = 0.002), a subset of preadipocytes that generates high lipolytic rate adipocytes ex vivo. Acute exercise did not alter EC content. Acute exercise also did not change total immune cell, macrophage, or T cell content, and future work should assess the effects of exercise on subpopulations of these cells. We conclude that exercise may rapidly regulate the subcutaneous adipose tissue preadipocyte pool in ways that may help attenuate the high lipolytic rates that are commonly found in obesity.

The effect of lifelong endurance exercise on cardiovascular structure and exercise function in women.

The beneficial effects of sustained or lifelong (>25years) endurance exercise on cardiovascular structure and exercise function have been largely established in men. The current findings indicate that committed (≥4weekly exercise sessions) lifelong exercise results in substantial benefits in exercise capacity ( ), cardiovascular function at submaximal and maximal exercise, left ventricular mass and compliance, and blood volume compared to similarly aged or even younger (middle-age) untrained women. Endurance exercise training should be considered a key strategy to prevent cardiovascular disease with ageing in women as well as men. This study was a retrospective, cross-sectional analysis of exercise performance and left ventricular (LV) morphology in 70 women to examine whether women who have performed regular, lifelong endurance exercise acquire the same beneficial adaptations in cardiovascular structure and function and exercise performance that have been reported previously in men. Three groups of women were examined: (1) 35 older (>60years) untrained women (older untrained, OU), (2) 13 older women who had consistently performed four or more endurance exercise sessions weekly for at least 25years (older trained, OT), and (3) 22middle-aged (range 35-59years) untrained women (middle-aged untrained, MU) as a reference control for the appropriate age-related changes. Oxygen uptake ( ) and cardiovascular function (cardiac output ( ); stroke volume (SV) acetylene rebreathing) were examined at rest, steady-state submaximal exercise and maximal exercise (maximal oxygen uptake, ). Blood volume (CO rebreathing) and LV mass (cardiac magnetic resonance imaging), plus invasive measures of static and dynamic chamber compliance were also examined. (p<0.001) and maximal exercise and SV were larger in older trained women compared to the two untrained groups (∼17% and ∼27% for and SV, respectively, versus MU; ∼40% and ∼38% versus OU, all p<0.001). Blood volume (mLkg-1 ) and LV mass index (gm-2 ) were larger in OT versus OU (∼11% and ∼16%, respectively, both P≤0.015) Static LV chamber compliance was greater in OT compared to both untrained groups (median (25-75%): MU: 0.065 (0.049-0.080); OU: 0.085 (0.061-0.138); OT: 0.047 (0.031-0.054), P≤0.053). Collectively, these findings indicate that lifetime endurance exercise appears to be extremely effective at preserving or even enhancing cardiovascular structure and function with advanced age in women.

Exercise: A Protective Measure or an "Open Window" for COVID-19? A Mini Review.

The coronavirus disease 2019 (COVID-19) has spread to at least 115 countries and caused an alarming number of deaths. The current outbreak has lead authorities from many countries to adopt several protective measures, including lockdown and social distancing. Although being a reasonable measure to counteract the COVID-19 contamination, the restrictive measures have limited individual's ability to perform exercise outdoors or in gyms and similar facilities, thus raising the risks for chronic health conditions related to a sedentary lifestyle. The recent exercise recommendations to counteract the potential deleterious effects of COVID-19-related lockdown have not fully addressed resistance exercise interventions as potential home-based exercise strategies. Additionally, the following questions have been constantly raised: (1) Is training status capable of protecting an individual from COVID-19 infection?; and (2) Can a single endurance or resistance exercise session acutely increase the risks for COVID-19 infection? Therefore, the current mini review aimed to focus on these two concerns, as well as to discuss the potential use of practical blood flow restriction and no load resistance training as possible resistance exercise strategies that could be performed during the current COVID-19 pandemic.

Can IGF-1 Serum Levels Really be Changed by Acute Physical Exercise? A Systematic Review and Meta-Analysis.

Physical exercise plays an important role in metabolic health, especially in the insulin-like growth factor-1 (IGF-1) system. The objective of this study was to perform a systematic review and meta-analysis to evaluate the effects of a single endurance and resistance exercise session on IGF-1 serum. The systematic review was performed in SPORTDiscus, MEDLINE, PubMed, and Google Scholar databases. All analyses are based on random-effect models. The study identified 249 records of which 21 were included. There was an effect of endurance exercise on total IGF-1 (P = .01), but not for free IGF-1 (P = .36). Resistance exercise similarly only affected total IGF-1 (P = .003) and not free IGF-1 (P = .37). The effect size indicated that total IGF-1 is more affected (ES = 0.81) by endurance than by resistance exercise (ES = 0.46). The present study showed that IGF-1 serum concentrations are altered by exercise type, but in conditions which are not well-defined. The systematic review and meta-analysis suggest that there is no determinant in serum IGF-1 changes for the exercise load characteristic. Therefore, physical exercise may be an alternative treatment to control changes in IGF-1 metabolism and blood concentration.

No effect of supplemented heat stress during an acute endurance exercise session in hypoxia on hepcidin regulation.

The purpose of the present study was to compare endurance exercise-induced hepcidin elevation among "normoxia", "hypoxia" and "combined heat and hypoxia". Twelve males (21.5 ± 0.3years, 168.1 ± 1.2cm, 63.6 ± 2.0kg) participated in the present study. They performed 60min of cycling at 60% of [Formula: see text] in either "heat and hypoxia" (HHYP; FiO2 14.5%, 32°C), "hypoxia" (HYP; FiO2 14.5%, 23°C) or "normoxia" (NOR; FiO2 20.9%, 23°C). After completing the exercise, participants remained in the prescribed conditions for 3h post-exercise. Blood samples were collected before, immediately and 3h after exercise. Plasma IL-6 level significantly increased immediately after exercise (P < 0.05), with no significant difference among the trials. A significant elevation in serum EPO was observed 3h after exercise in hypoxic trials (HHYP and HYP, P < 0.05), with no significant difference between HHYP and HYP. Serum hepcidin level increased 3h after exercise in all trials (NOR, before 18.3 ± 3.9 and post180 31.2 ± 6.3ng/mL; HYP, before 13.5 ± 2.5 and post180 23.3 ± 3.6ng/mL, HHYP; before 15.8 ± 3.3 and post180 31.4 ± 5.3ng/mL, P < 0.05). However, there was no significant difference among the trials during post-exercise. Endurance exercise in "combined heat and hypoxia" did not exacerbate exercise-induced hepcidin elevation compared with the same exercise in "hypoxia" or "normoxia".

Cellular immune response to acute exercise: Comparison of endurance and resistance exercise.

Exercise-induced cellular mobilization might play a role in treatment and prevention of several diseases. However, little is known about the impact of different exercise modalities on immune cell mobilization and clinical cellular inflammation markers. Therefore, the present study aimed to investigate differences between acute endurance exercise (EE) and resistance exercise (RE) on cellular immune alterations. Twenty-four healthy men conducted an acute EE (cycling at 60% of peak power output) and RE (five exercise machines at 70% of the one-repetition maximum) session lasting 50minutes in randomized order. Blood samples were collected before, after and one hour after exercise cessation. Outcomes included counts and proportions of leukocytes, neutrophils (NEUT), lymphocytes (LYM), LYM subsets, CD4/CD8 ratio, and the clinical cellular inflammation markers NEUT/LYM ratio (NLR), platelets/LYM ratio (PLR), and systemic immune inflammation index (SII). Alterations in all outcomes were revealed except for CD8+ T cells, CD4/CD8 ratio, NLR, and PLR. EE induced a stronger cellular immune response and provoked alterations in more immune cell populations than RE. SII was altered only after EE. An acute EE session causes a stronger mobilization of immune cells than RE. Additionally, SII represents an integrative marker to depict immunological alterations.

Effect of Endurance Exercise Along with Strawberry Supplementation on Lipid Profile and Inflammatory Markers in Overweight and Inactive Young Women

Background: Herbal supplementation with moderate- and high-intensity aerobic exercise affects obesity-related factors, especially the lipid profile and inflammatory markers. Objectives: The present study was conducted to determine the effect of endurance training with strawberry extract supplementation on inflammatory markers and the lipid profile in healthy inactive women. Methods: The subjects included inactive women aged 20 - 30 years, who were randomly divided into two groups: (a) The endurance exercise + supplementation group (n = 12) and (b) The endurance exercise + placebo group (n = 12). The supplementation group received 100-mg strawberry extract supplement twice per day for two weeks. After the supplementation, the exercise protocol was carried out, which included a session of endurance exercise within 75% - 80% of the maximum heart rate on the treadmill for 30 minutes. Blood samples were taken before and after the intervention to determine the lipid profile and plasma fibrinogen concentration. Data were analyzed using the repeated-measures ANOVA. Results: The results showed a significant reduction in TC, TG and LDL-C and a significant increase in HDL-C after the supplementation, but no significant changes were observed in the placebo group. Fibrinogen concentrations decreased significantly following the supplementation. Meanwhile, no significant increase was observed in the groups after the endurance exercise (P ≤ 0.05). Conclusions: According to the results obtained and the benefits of dried strawberry powder on cardiovascular risk factor control, supplementation following exercise training are recommended for improving the physiological function of inactive people who are prone to dyslipidemia and inflammation.

287-OR: Acute Exercise Enhances the Differentiation Rate of Human Adipocyte Precursor Cells

The direct effects of exercise on white adipose tissue morphology and metabolic function remain unclear, due in large part to confounding effects of the reduction in fat mass that often accompanies exercise training. The purpose of this study was to determine if a session of endurance exercise could impact the rate of adipogenesis. Eight lean, healthy human subjects performed a single session of exercise (1 hour of endurance exercise at 65% of their maximal aerobic capacity; VO2max). Blood samples were collected without prior exercise (No-EX) and immediately after exercise (EX). Serum was extracted, and human adipocyte precursor cells were incubated for 72 hours in vitro in either the No-EX or EX serum. This serum preincubation was immediately followed by a standard 14-day differentiation protocol. On both days 3 and 9 of differentiation, mRNA expression levels of differentiation markers, PPARG and FABP4, were significantly greater (P&amp;lt;0.01) in cells preincubated in the EX vs. No-EX serum (e.g., Day 3 PPARG expression: 11.4±0.6 vs. 8.3±0.4 2-∆Ct; P=0.005, and Day 9 FABP4 expression: 2185±82 vs. 1619±98 2-∆Ct; P&amp;lt;0.0001). In addition, after 14 days of differentiation, we also found significantly greater protein abundance of important lipolytic and esterification regulators, G0S2, ATGL, HSL and GPAT1 (all P&amp;lt;0.05). As expected, compared with No-EX, the EX sera had greater concentrations of IL-6, lactate, fatty acids, epinephrine, and growth hormone, some of which may contribute to the enhanced adipogenic signaling after exercise. In summary, factors released into the circulation during and/or immediately after a session of endurance exercise can accelerate the rate of differentiation in human adipocyte precursor cells. Enhanced adipogenic signaling in response to exercise may have metabolic health benefits by priming adipose tissue for a more effective energy storage during periods of weight gain. Disclosure P. Varshney: None. L.M. Guth: None. C.M. Anderson: None. A. Raajendiran: None. M.J. Watt: None. J.F. Horowitz: Research Support; Self; American Diabetes Association. Funding National Institutes of Health (R01DK077966, T32DK101357)

750-P: Oral Carbohydrate Demand during Endurance Exercise Is Dependent on Pre-exercise Blood Glucose Concentration in People with Type 1 Diabetes: A Randomized Crossover Trial

Aim: To investigate the impact of moderate-intensity exercise and pre-exercise blood glucose concentrations (BG) on the demand of orally administered carbohydrates (CHO) to maintain euglycemia (&amp;gt; 70 - 180 mg/dL) during endurance exercise sessions performed over 5 consecutive days on either a regular (100%) or reduced dose (75%) of insulin degludec (IDeg) in people with type 1 diabetes (T1D). Methods: Nine participants with T1D (four women, mean age 32.1 ± 9.0 years, BMI 25.5 ± 3.9 kg/m2, glycated hemoglobin 55 ± 7 mmol/mol [7.2 ± 0.6%]) on IDeg were randomized to cycle for 55 minutes at moderate intensity (63 ± 7% VO2max) for 5 consecutive days on either 100% or 75% of their regular IDeg dose. The exercise accumulating effect was analysed via one-way-ANOVA for repeated measures (day x administered CHO). The influence of pre-exercise BG was analysed by one-way ANOVA or Kruskal-Wallis stratified for BG quartiles and Spearman correlation. The effect of IDeg dose (100% vs. 75%) on given CHO was calculated via Wilcoxon or student's t-test (p&amp;lt;0.05). Results: No exercise accumulating effect was found (p&amp;gt;0.05) but CHO intake was significantly related to pre-exercise BG (r=-0.45; p&amp;lt;0.0001). Conclusion: Pre-exercise BG had a significant influence on the demand of orally administered CHO to maintain euglycemia during exercise over 5 consecutive days. Disclosure M.L. Eckstein: Research Support; Self; Novo Nordisk A/S. O. Moser: Research Support; Self; Abbott, Dexcom, Inc., Novo Nordisk A/S. A. Mueller: None. P. Birnbaumer: None. F. Aberer: None. G. Koehler: Advisory Panel; Self; Boehringer Ingelheim International GmbH, Lilly Diabetes, Novo Nordisk A/S. Speaker's Bureau; Self; Boehringer Ingelheim International GmbH, Lilly Diabetes, Novo Nordisk A/S, Sanofi-Aventis Deutschland GmbH. C. Sourij: None. H. Kojzar: None. P.N. Pferschy: None. P. Dietz: None. R.M. Bracken: None. P. Hofmann: None. H. Sourij: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Merck Sharp &amp; Dohme Corp., Novo Nordisk A/S, Sanofi-Aventis. Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Merck Sharp &amp; Dohme Corp., Novo Nordisk A/S, Novo Nordisk A/S, Sanofi-Aventis. Speaker’s Bureau; Self; Amgen Inc., AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Merck Sharp &amp; Dohme Corp., Novo Nordisk A/S, Sanofi-Aventis. Funding Novo Nordisk Pharma GmbH

Feasibility and Preliminary Effects of a Telerehabilitation Program for People Living With HIV: A Pilot Randomized Study.

We investigated feasibility and preliminary effects of telerehabilitation for people living with HIV (PLWH) and taking antiretroviral therapy. We randomized 25 PLWH to either an endurance and resistance training exercise (ERTE) group or a control group. Endurance and resistance training exercise sessions occurred in a public fitness center, with online guidance and weekly telephone advice. The primary outcome was feasibility (recruitment and retention rates and safety). Secondary outcomes were assessed at baseline and 6 weeks according to the three International Classification of Functioning, Disability, and Health domains. Nine patients completed the ERTE program. Recruitment and retention rates were 93% and 69%, respectively. No adverse events occurred. After 6 weeks, percentage change in D-dimer was lower in the ERTE group, but not significantly after the Bonferroni correction. Other parameters were not different between the groups. Therefore, telerehabilitation is feasible in PLWH taking antiretroviral therapy; however, the performance of the program is still questioned, and future research is warranted.

Expectation of exercise in trained athletes results in a reduction of central processing to nociceptive stimulation

A single endurance exercise session was shown to lead to a reduction of pain perception and an elevation of mood. We hypothesized that athletes, who regularly practice endurance, might also induce changes in mood and pain processing in expectation of an endurance session. We compared the expectation effects of a 2-h-run on mood and pain processing to a run-free control day (RFC). Fifteen trained runners were assessed with repeated painful and nonpainful pinprick stimulation in a functional magnetic resonance imaging (fMRI) scanner prior to a 2-h-run and at RFC. Pain ratings, pressure pain stimulus-response functions, and euphoria ratings were also assessed. There were no mean expectation effects on any of the behavioral measures. However, highly trained athletes needed more pressure to evoke a pain rating of 46 pre-run vs. RFC but were less euphoric pre-run vs. RFC. Furthermore, analysis of brain activities to painful stimuli applied immediately before the 2-h-run compared to RFC revealed increased activation in the medial prefrontal cortex (mPFC) and reduced activation in posterior insula. Additionally, less trained athletes had reduced activation in posterior insula to painful stimulation pre-run vs. RFC compared to highly trained athletes. The results suggest reduced central pain processing in expectation of an endurance run and an association between the amount of the expectation effect and training frequency which differs depending on the stimuli applied.

The Influence of Post-Exercise Cold-Water Immersion on Adaptive Responses to Exercise: A Review of the Literature.

Post-exercise cold-water immersion (CWI) is used extensively in exercise training as a means to minimise fatigue and expedite recovery between sessions. However, debate exists around its merit in long-term training regimens. While an improvement in recovery following a single session of exercise may improve subsequent training quality and stimulus, reports have emerged suggesting CWI may attenuate long-term adaptations to exercise training. Recent developments in the understanding of the molecular mechanisms governing the adaptive response to exercise in human skeletal muscle have provided potential mechanistic insight into the effects of CWI on training adaptations. Preliminary evidence suggests that CWI may blunt resistance signalling pathways following a single exercise session, as well as attenuate key long-term resistance training adaptations such as strength and muscle mass. Conversely, CWI may augment endurance signalling pathways and the expression of genes key to mitochondrial biogenesis following a single endurance exercise session, but have little to no effect on the content of proteins key to mitochondrial biogenesis following long-term endurance training. This review explores current evidence regarding the underlying molecular mechanisms by which CWI may alter cellular signalling and the long-term adaptive response to exercise in human skeletal muscle.

Post-exercise serum hepcidin levels were unaffected by hypoxic exposure during prolonged exercise sessions.

The purpose of the present study was to determine the influence of hypoxic exposure during prolonged endurance exercise sessions (79 min in total) on post-exercise hepcidin levels in trained male endurance athletes. Ten endurance athletes (mean ± standard deviation; height: 169.8 ± 7.1 cm, weight: 57.1 ± 5.0 kg) conducted two endurance exercise sessions under either a normobaric hypoxic condition [inspired O2 fraction (FiO2) = 14.5%] or a normoxic condition (FiO2 = 20.9%). Exercise consisted of 10 × 3 min running on a treadmill at 95% of maximal oxygen uptake () with 60s of active rest at 60% of . After 10 min of rest, they subsequently performed 30 min of continuous running at 85% of . Running velocities were significantly lower in the HYPO than in the NOR (P < 0.0001). Exercise-induced blood lactate elevation was significantly greater in the HYPO (P < 0.01). There were significant increases in plasma interleukin-6, serum iron, and blood glucose levels after exercise, with no significant difference between the trials [interaction (trial × time) or main effect for trial, P > 0.05]. Serum hepcidin levels increased significantly 120 min after exercise (HYPO: from 10.7 ± 9.4 ng/mL to 15.8 ± 11.2 ng/mL; NOR: from 7.9 ± 4.7 ng/mL to 13.2 ± 7.9 ng/mL, P < 0.05), and no difference was observed between the trials. In conclusion, endurance exercise at lower running velocity in hypoxic conditions resulted in similar post-exercise hepcidin elevations as higher running velocity in normoxic conditions.

Acute and chronic effects of exercise on mRNA expression in the skeletal muscle of two mouse models of peripheral artery disease.

Endurance exercise improves walking performance in patients with peripheral artery disease (PAD), which is characterized by skeletal muscle dysfunction caused by lower extremity ischemia. Although transcriptional analyses of exercise-induced changes in normal animals and healthy volunteers have been reported, no detailed study has explored exercise-induced alterations in gene expression in PAD animal models. Here, we determined the acute and chronic effects of exercise on mRNA expression in the skeletal muscles of two mouse models of PAD. Three particular gene categories were investigated: known exercise-responsive genes (Pgc1a, Il6, Nr4a1, Nr4a2, and Nr4a3); myogenic and muscle regeneration-related genes (Myf5, Myogenin, Myomaker, and Myh3); and Gpr56 and its ligand Col3a1. PAD was induced by bilateral femoral artery ligation in normal C57BL/6 and diabetic KK-Ay mice. From 1 week after surgery, repetitive twice-weekly 30-min treadmill endurance exercise sessions were applied. Altered mRNA expression in the soleus muscles was measured in both the acute and chronic phases. In the acute phase, transcript levels of exercise-inducible genes showed significant increases in both C57BL/6 and diabetic KK-Ay PAD mice; levels of regeneration-related genes showed little alteration, and those of Gpr56 increased immediately and significantly after exercise in both models. In the chronic phase, transcript levels of Pgc1a, Myf5, Myogenin, Myomaker, Myh3, Gpr56, and Col3a1 were upregulated significantly in sedentary C57BL/6 PAD mice compared with that in sham-operated mice. Exercise training inhibited the upregulation of Col3a1, Myf5, and Myogenin significantly. In KK-Ay PAD mice, only Gpr56 mRNA levels increased significantly compared with those in sham-operated mice. RNA sequence analysis revealed 33 and 166 differentially upregulated, and 363 and 99 downregulated, genes after exercise training in C57BL/6 PAD and KK-Ay PAD mice, respectively. In summary, we detected significant alterations of skeletal muscle genes after exercise in PAD mouse models and characterized their expression patterns.

Design of a randomized controlled trial of physical training and cancer (Phys-Can) \u2013 the impact of exercise intensity on cancer related fatigue, quality of life and disease outcome

BackgroundCancer-related fatigue is a common problem in persons with cancer, influencing health-related quality of life and causing a considerable challenge to society. Current evidence supports the beneficial effects of physical exercise in reducing fatigue, but the results across studies are not consistent, especially in terms of exercise intensity. It is also unclear whether use of behaviour change techniques can further increase exercise adherence and maintain physical activity behaviour. This study will investigate whether exercise intensity affects fatigue and health related quality of life in persons undergoing adjuvant cancer treatment. In addition, to examine effects of exercise intensity on mood disturbance, adherence to oncological treatment, adverse effects from treatment, activities of daily living after treatment completion and return to work, and behaviour change techniques effect on exercise adherence. We will also investigate whether exercise intensity influences inflammatory markers and cytokines, and whether gene expressions following training serve as mediators for the effects of exercise on fatigue and health related quality of life.Methods/designSix hundred newly diagnosed persons with breast, colorectal or prostate cancer undergoing adjuvant therapy will be randomized in a 2 × 2 factorial design to following conditions; A) individually tailored low-to-moderate intensity exercise with or without behaviour change techniques or B) individually tailored high intensity exercise with or without behaviour change techniques. The training consists of both resistance and endurance exercise sessions under the guidance of trained coaches. The primary outcomes, fatigue and health related quality of life, are measured by self-reports. Secondary outcomes include fitness, mood disturbance, adherence to the cancer treatment, adverse effects, return to activities of daily living after completed treatment, return to work as well as inflammatory markers, cytokines and gene expression.DiscussionThe study will contribute to our understanding of the value of exercise and exercise intensity in reducing fatigue and improving health related quality of life and, potentially, clinical outcomes. The value of behaviour change techniques in terms of adherence to and maintenance of physical exercise behaviour in persons with cancer will be evaluated.Trial registrationNCT02473003, October, 2014.

Cortisol and testosterone dynamics following exhaustive endurance exercise.

Cortisol (C) and testosterone (T) are impacted significantly by prolonged endurance exercise with inverse responses. Increases in C are witnessed concurrently with decrements in T, possibly impacting recovery. This study was conducted to assess the dynamics of C and free T (fT) concentration and recovery time following an exhaustive endurance exercise session (EES). 12 endurance-trained males (X±SD: VO2max 66.3±4.8ml/kg/min, age 22.8±3.1years, body fat 11.0±1.4%, training 7.1±3.2years) completed a treadmill EES at ventilatory threshold (74.7±4.6% of VO2max; 96.9±10.8min). Basal blood C and fT were collected at baseline: -48, -24h, and immediately before (0h) the EES as well as immediately (+0h), +24h, +48h, and +72h after the EES. Blood glucose (G) was measured to confirm no undue influence on C. Statistically data were analyzed with repeated measures ANOVA (LSD post hoc). C (nmol/L) increased significantly from -48h (321±59) to +0h (701±178) (p<0.001), and displayed a baseline overshoot with +24h (209±67) being significantly lower than -48 and +0h (p<0.03). fT (pmol/L) decreased significantly from -48h (161±40) to +0h (106±38) (p<0.01) and remained lower at +24h (110±33) and +48h (129±30) (p<0.001). G remained stable throughout. A moderately negative correlation (r=-0.636, p<0.026) was found between C and fT at +0h. EES recovery may require 48h for C and 72h for fT to return to baseline values. Furthermore, C and fT were only correlated immediately post-exercise. Future research should perform more frequent measurements throughout time course.

Minimum Cost of Transport in Human Running Is Not Ubiquitous

This study explores recent claims that humans exhibit minimum cost of transport (CoTmin) for running, which occurs at intermediate speed, and assesses individual physiological, gait, and training characteristics. Twelve healthy participants with varying levels of fitness and running experience ran on a treadmill at six self-selected speeds in a discontinuous protocol over three sessions. Running speed (km·h), VO2 (mL·kg·km), CoT (kcal·km), HR (bpm), and cadence (steps per minute) were continuously measured. VO2max was measured on the fourth testing session. The occurrence of CoTmin was investigated, and its presence or absence was examined with respect to fitness, gait, and training characteristics. Five participants showed clear CoTmin at intermediate speed and a statistically significant (P < 0.05) quadratic CoT-speed function, whereas the other participants did not show such evidence. Participants were then categorized and compared with respect to the strength of evidence for CoTmin (ClearCoTmin and NoCoTmin). The ClearCoTmin group displayed a significantly higher correlation between speed and cadence, more endurance training and exercise sessions per week, and a marginally nonsignificant but higher aerobic capacity than the NoCoTmin group. Some runners still showed CoTmin at intermediate speed even after subtraction of resting energy expenditure. The findings confirm the existence of optimal speed for human running in some but not all participants. Those exhibiting COTmin undertook higher volume of running, ran with a cadence that was more consistently modulated with speed, and tended to be aerobically fitter. The ability to minimize energetic CoT seems not to be a ubiquitous feature of human running but may emerge in some individuals with extensive running experience.

The effect of lifelong exercise dose on cardiovascular function during exercise

An increased "dose" of endurance exercise training is associated with a greater maximal oxygen uptake (Vo2max), a larger left ventricular (LV) mass, and improved heart rate and blood pressure control. However, the effect of lifelong exercise dose on metabolic and hemodynamic response during exercise has not been previously examined. We performed a cross-sectional study on 101 (69 men) seniors (60 yr and older) focusing on lifelong exercise frequency as an index of exercise dose. These included 27 who had performed ≤ 2 exercise sessions/wk (sedentary), 25 who performed 2-3 sessions/wk (casual), 24 who performed 4-5 sessions/wk (committed) and 25 who performed ≥ 6 sessions/wk plus regular competitions (Masters athletes) over at least the last 25 yr. Oxygen uptake and hemodynamics [cardiac output, stroke volume (SV)] were collected at rest, two levels of steady-state submaximal exercise, and maximal exercise. Doppler ultrasound measures of LV diastolic filling were assessed at rest and during LV loading (saline infusion) to simulate increased LV filling. Body composition, total blood volume, and heart rate recovery after maximal exercise were also examined. Vo2max increased in a dose-dependent manner (P < 0.05). At maximal exercise, cardiac output and SV were largest in committed exercisers and Masters athletes (P < 0.05), while arteriovenous oxygen difference was greater in all trained groups (P < 0.05). At maximal exercise, effective arterial elastance, an index of ventricular-arterial coupling, was lower in committed exercisers and Masters athletes (P < 0.05). Doppler measures of LV filling were not enhanced at any condition, irrespective of lifelong exercise frequency. These data suggest that performing four or more weekly endurance exercise sessions over a lifetime results in significant gains in Vo2max, SV, and heart rate regulation during exercise; however, improved SV regulation during exercise is not coupled with favorable effects on LV filling, even when the heart is fully loaded.

Energy Expenditure during Sexual Activity in Young Healthy Couples

ObjectiveTo determine energy expenditure in kilocalories (kcal) during sexual activity in young healthy couples in their natural environment and compare it to a session of endurance exercise.MethodsThe study population consisted of twenty one heterosexual couples (age: 22.6 ± 2.8 years old) from the Montreal region. Free living energy expenditure during sexual activity and the endurance exercise was measured using the portable mini SenseWear armband. Perceived energy expenditure, perception of effort, fatigue and pleasure were also assessed after sexual activity. All participants completed a 30 min endurance exercise session on a treadmill at a moderate intensity.ResultsMean energy expenditure during sexual activity was 101 kCal or 4.2 kCal/min in men and 69.1 kCal or 3.1 kCal/min in women. In addition, mean intensity was 6.0 METS in men and 5.6 METS in women, which represents a moderate intensity. Moreover, the energy expenditure and intensity during the 30 min exercise session in men was 276 kCal or 9.2 kCal/min and 8.5 METS, respectively and in women 213 kCal or 7.1 kCal/min and 8.4 METS, respectively. Interestingly, the highest range value achieved by men for absolute energy expenditure can potentially be higher than that of the mean energy expenditure of the 30 min exercise session (i.e. 306.1 vs. 276 kCal, respectively) whereas this was not observed in women. Finally, perceived energy expenditure during sexual activity was similar in men (100 kCal) and in women (76.2 kCal) when compared to measured energy expenditure.ConclusionThe present study indicates that energy expenditure during sexual activity appears to be approximately 85 kCal or 3.6 kCal/min and seems to be performed at a moderate intensity (5.8 METS) in young healthy men and women. These results suggest that sexual activity may potentially be considered, at times, as a significant exercise.

Thyroid hormonal responses to intensive interval versus steady-state endurance exercise sessions

To compare the thyroid hormonal responses to high-intensity interval exercise (IE) and steady-state endurance exercise (SEE) in highly trained males (n=15). The IE session consisted of repeated periods of 90-seconds treadmill running at 100-110% VO(2max) and 90-seconds active recovery at 40% VO(2max) for 42-47 minutes. The SEE session was a 45-minute run at 60-65% VO(2max). Total work output was equal for each session. A 45-minute supine rest control session (CON) was also performed. Pre-session (PRE), immediate post-session (POST), and 12-hours post-session (12POST) blood samples were collected and used to determine free (f) T₄, fT₃, reverse (r) T₃, and cortisol levels. All PRE hormone levels were within clinical norms and did not differ significantly between sessions. All POST IE and SEE hormone levels were significantly elevated compared to POST CON (p<0.001). At 12POST, no significant differences between CON and SEE hormonal levels were observed; however, fT₃ was significantly reduced and rT3 was significantly elevated in 12POST IE compared to 12POST SEE and CON (p=0.022). For IE, at 12POST a negative correlation (r(s) = -0.70, p<0.004) was found between fT₃ and rT₃.Also, for IE, a positive correlation (r(s) = 0.74, p<0.002) between cortisol POST and rT₃ 12POST was noted, and a negative correlation (r(s) = -0.72, p<0.003) between cortisol POST and fT₃ 12POST. IE results in a suppressed peripheral conversion of T₄ to T₃ implying that a longer recovery period is necessary for hormonal levels to return to normal following IE compared to SEE. These findings are useful in the implementation of training regimens relative to recovery needs and prevention of over-reaching-overtraining.