Circulating angiogenic and inflammatory cytokine responses to acute aerobic exercise in trained and sedentary young men

Purpose

Endurance exercise training can ameliorate many cardiovascular and metabolic disorders and attenuate responses to inflammatory stimuli. The purpose of this study was to determine whether the angiogenic and pro-inflammatory cytokine response to acute endurance exercise differs between endurance-trained and sedentary young men.

Methods

Ten endurance-trained and ten sedentary healthy young men performed 30 min of treadmill running at 75 % VO_2max with blood sampling before and after exercise. Plasma concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-8, IL-6, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), placental growth factor (PlGF), and soluble VEGF receptor-1 (sFlt-1) were measured by multiplex ELISA.

Results

Acute exercise increased IL-6 by 165 % (P < 0.05), IL-8 by 32 % (P < 0.05), PlGF by ~16 % (P < 0.05), sFlt-1 by 36 % (P < 0.001), and tended to increase bFGF by ~25 % (P = 0.06) in main effects analyses. TNF-α and VEGF did not change significantly with exercise in either group. Contrary to our hypothesis, there were no significant differences in TNF-α, IL-6, VEGF, bFGF, PlGF, or sFlt-1 between groups before or after acute exercise; however, there was a tendency for IL-8 concentrations to be higher in endurance-trained subjects compared to sedentary subjects (P = 0.06).

Conclusions

These results indicate that 30 min of treadmill running at 75 % VO_2max produces a systemic angiogenic and inflammatory reaction, but endurance exercise training does not appear to significantly alter these responses in healthy young men.     

Effects of probiotics supplementation on gastrointestinal permeability, inflammation and exercise performance in the heat

Purpose

This study aimed to investigate the effects of multi-strain probiotics supplementation on gastrointestinal permeability, systemic markers of inflammation and running performance when exercising in the heat.

Methods

Ten male runners were randomized to 4 weeks of daily supplementation with a probiotics capsule (45 billion CFU of Lactobacillus, Bifidobacterium and Streptococcus strains) or placebo, separated by a washout period (double-blind, cross-over trial). After each treatment, the runners exercised to fatigue at 80 % of their ventilatory threshold at 35 °C and 40 % humidity. To assess gastrointestinal permeability, runners ingested lactulose and rhamnose before exercise and post-exercise urine was collected to measure sugar concentrations. Venous blood samples were collected before, immediately after and 1 h after exercise, and core temperature was monitored during exercise.

Results

Probiotics supplementation significantly increased run time to fatigue (min:s 37:44 ± 2:42 versus 33:00 ± 2:27; P = 0.03, d = 0.54). Average core temperature during exercise was similar between trials (probiotic 38.1 ± 0.2 °C, placebo 38.1 ± 0.1 °C; P = 0.77, d = 0.13). Serum lipopolysaccharide concentration increased post-exercise (P < 0.001), while there was a moderate to large reduction in pre-exercise (d = 0.70) and post-exercise (d = 1.24) concentration following probiotics supplementation. Plasma concentrations of IL-6, IL-10 and IL-1ra increased after exercise (P < 0.01), but there was no significant difference between trials (P > 0.05). There was a small to moderate reduction (d = 0.35) in urine lactulose:rhamnose and a small reduction (d = 0.25) in symptoms of gastrointestinal discomfort following probiotics supplementation (both P = 0.25).

Conclusion

Four weeks of supplementation with a multi-strain probiotic increased running time to fatigue in the heat. Further studies are required to elucidate the exact mechanisms for this performance benefit.     

Appetite, gut hormone and energy intake responses to low volume sprint interval and traditional endurance exercise

Sprint interval exercise improves several health markers but the appetite and energy balance response is unknown. This study compared the effects of sprint interval and endurance exercise on appetite, energy intake and gut hormone responses. Twelve healthy males [mean (SD): age 23 (3) years, body mass index 24.2 (2.9) kg m^?2, maximum oxygen uptake 46.3 (10.2) mL kg^?1 min^?1] completed three 8 h trials [control (CON), endurance exercise (END), sprint interval exercise (SIE)] separated by 1 week. Trials commenced upon completion of a standardised breakfast. Sixty minutes of cycling at 68.1 (4.3) % of maximum oxygen uptake was performed from 1.75–2.75 h in END. Six 30-s Wingate tests were performed from 2.25–2.75 h in SIE. Appetite ratings, acylated ghrelin and peptide YY (PYY) concentrations were measured throughout each trial. Food intake was monitored from buffet meals at 3.5 and 7 h and an overnight food bag. Appetite (P < 0.0005) and acylated ghrelin (P < 0.002) were suppressed during exercise but more so during SIE. Peptide YY increased during exercise but most consistently during END (P < 0.05). Acylated ghrelin was lowest in the afternoon of SIE (P = 0.018) despite elevated appetite (P = 0.052). Exercise energy expenditure was higher in END than that in SIE (P < 0.0005). Energy intake was not different between trials (P > 0.05). Therefore, relative energy intake (energy intake minus the net energy expenditure of exercise) was lower in END than that in CON (15.7 %; P = 0.006) and SIE (11.5 %; P = 0.082). An acute bout of endurance exercise resulted in lower appetite perceptions in the hours after exercise than sprint interval exercise and induced a greater 24 h energy deficit due to higher energy expenditure during exercise.     

Influence of the world’s most challenging mountain ultra-marathon on energy cost and running mechanics

Purpose

To examine the effects of the world’s most challenging mountain ultra-marathon (Tor des Géants^® 2012) on the energy cost of three types of locomotion (cycling, level and uphill running) and running kinematics.

Methods

Before (pre-) and immediately after (post-) the competition, a group of ten male experienced ultra-marathon runners performed in random order three submaximal 4-min exercise trials: cycling at a power of 1.5 W kg^?1 body mass; level running at 9 km h^?1 and uphill running at 6 km h^?1 at an inclination of +15 % on a motorized treadmill. Two video cameras recorded running mechanics at different sampling rates.

Results

Between pre- and post-, the uphill-running energy cost decreased by 13.8 % (P = 0.004); no change was noted in the energy cost of level running or cycling (NS). There was an increase in contact time (+10.3 %, P = 0.019) and duty factor (+8.1 %, P = 0.001) and a decrease in swing time (?6.4 %, P = 0.008) in the uphill-running condition.

Conclusion

After this extreme mountain ultra-marathon, the subjects modified only their uphill-running patterns for a more economical step mechanics.     

Alterations in amino acid concentrations in the plasma and muscle in human subjects during 24 h of simulated adventure racing

This investigation was designed to evaluate changes in plasma and muscle levels of free amino acids during an ultra-endurance exercise and following recovery. Nine male ultra-endurance trained athletes participated in a 24-h standardized endurance trial with controlled energy intake. The participants performed 12 sessions of running, kayaking and cycling (4 × each discipline). Blood samples were collected before, during and after exercise, as well as after 28 h of recovery. Muscle biopsies were taken before the test and after exercise, as well as after 28 h of recovery. During the 24-h exercise, plasma levels of branched-chain (BCAA), essential amino acids (EAA) and glutamine fell 13, 14 and 19% (P < 0.05), respectively, whereas their concentrations in muscle were unaltered. Simultaneously, tyrosine and phenylalanine levels rose 38 and 50% (P < 0.05) in the plasma and 66 and 46% (P < 0.05) in muscle, respectively. After the 24-h exercise, plasma levels of BCAA were positively correlated with muscle levels of glycogen (r ² = 0.73, P < 0.05), as was the combined concentrations of muscle tyrosine and phenylalanine with plasma creatine kinase (R ² = 0.55, P < 0.05). Following 28-h of recovery, plasma and muscle levels of amino acids had either returned to their initial levels or were elevated. In conclusion, ultra-endurance exercise caused significant changes elevations in plasma and muscle levels of tyrosine and phenylalanine, which suggest an increase in net muscle protein breakdown during exercise. There was a reduction in plasma concentrations of EAA and glutamine during exercise, whereas no changes were detected in their muscle concentration after exercise.     

High-load resistance exercise with superimposed vibration and vascular occlusion increases critical power, capillaries and lean mass in endurance-trained men

Purpose

It is a widely accepted premise in the scientific community and by athletes alike, that adding resistance exercise to a regular regimen of endurance training increases endurance performance in endurance-trained men. However, critical power (CP), capillarization, and myofiber size remain unaffected by this addition. Therefore, we tested whether the superimposition of resistance exercise with whole-body vibration and vascular occlusion (vibroX) would improve these variables in endurance-trained males relative to resistance exercise alone.

Methods

Twenty-one young, endurance-trained males were randomly assigned either to a vibroX (n = 11) or resistance (n = 10) training group. Both groups trained in a progressive mode twice a week for 8 weeks. Pre and post training, histochemical muscle characteristics, thigh muscle size, endurance and strength parameters were determined.

Results

vibroX increased CP (P = 0.001), overall capillary-to-fiber ratio (P = 0.001) and thigh lean mass (P < 0.001), while these parameters were unaffected by resistance training. The gain in CP by vibroX was positively correlated with the gain in capillarization (R ² = 0.605, P = 0.008), and the gain in thigh lean mass was paralleled by increases in MyHC-1 and MyHC-2 fiber cross-sectional areas and strength. Maximum voluntary torque and the finite work capacity above CP (W′) increased significantly only following resistance training.

Conclusions

We achieved a proof of concept by demonstrating that modification of resistance exercise by superimposing side-alternating whole-body vibration and sustained vascular occlusion induced further improvements in CP, capillarization and hypertrophy, all of which were not observed with resistance training alone.     

Exercise volume and intensity: a dose–response relationship with health benefits

Introduction

The health benefits of exercise are well established. However, the relationship between exercise volume and intensity and health benefits remains unclear, particularly the benefits of low-volume and intensity exercise.

Purpose

The primary purpose of this investigation was, therefore, to examine the dose–response relationship between exercise volume and intensity with derived health benefits including volumes and intensity of activity well below international recommendations.

Methods

Generally healthy, active participants (n = 72; age = 44 ± 13 years) were assigned randomly to control (n = 10) or one of five 13-week exercise programs: (1) 10-min brisk walking 1×/week (n = 10), (2) 10-min brisk walking 3×/week (n = 10), (3) 30-min brisk walking 3×/week (n = 18), (4) 60-min brisk walking 3×/week (n = 10), and (5) 30-min running 3×/week (n = 14), in addition to their regular physical activity. Health measures evaluated pre- and post-training including blood pressure, body composition, fasting lipids and glucose, and maximal aerobic power (VO₂max).

Results

Health improvements were observed among programs at least 30 min in duration, including body composition and VO₂max: 30-min walking 28.8–34.5 mL kg^?1 min^?1, 60-min walking 25.1–28.9 mL kg^?1 min^?1, and 30-min running 32.4–36.4 mL kg^?1 min^?1. The greater intensity running program also demonstrated improvements in triglycerides.

Conclusion

In healthy active individuals, a physical activity program of at least 30 min in duration for three sessions/per week is associated with consistent improvements in health status.     

Compression stockings do not improve muscular performance during a half-ironman triathlon race

Purpose

This study aimed at investigating the effectiveness of compression stockings to prevent muscular damage and preserve muscular performance during a half-ironman triathlon.

Methods

Thirty-six experienced triathletes volunteered for this study. Participants were matched for age, anthropometric data and training status and placed into the experimental group (N = 19; using ankle-to-knee graduated compression stockings) or control group (N = 17; using regular socks). Participants competed in a half-ironman triathlon celebrated at 29 ± 3 °C and 73 ± 8 % of relative humidity. Race time was measured by means of chip timing. Pre- and post-race, maximal height and leg muscle power were measured during a countermovement jump. At the same time, blood myoglobin and creatine kinase concentrations were determined and the triathletes were asked for perceived exertion and muscle soreness using validated scales.

Results

Total race time was not different between groups (315 ± 45 for the control group and 310 ± 32 min for the experimental group; P = 0.46). After the race, jump height (?8.5 ± 3.0 versus ?9.2 ± 5.3 %; P = 0.47) and leg muscle power reductions (?13 ± 10 versus ?15 ± 10 %; P = 0.72) were similar between groups. Post-race myoglobin (718 ± 119 versus 591 ± 100 μg/mL; P = 0.42) and creatine kinase concentrations (604 ± 137 versus 525 ± 69 U/L; P = 0.60) were not different between groups. Perceived muscle soreness (5.3 ± 2.1 versus 6.0 ± 2.0 arbitrary units; P = 0.42) and the rating of perceived effort (17 ± 2 versus 17 ± 2 arbitrary units; P = 0.58) were not different between groups after the race.

Conclusion

Wearing compression stockings did not represent any advantage for maintaining muscle function or reducing blood markers of muscle damage during a triathlon event.     

Operating lung volumes are affected by exercise mode but not trunk and hip angle during maximal exercise

Introduction

Despite VO_2peak being, generally, greater while running compared to cycling, ventilation (V _E) during maximal exercise is less while running compared to cycling. Differences in operating lung volumes (OLV) between maximal running and cycling could be one explanation for previously observed differences in V _E and this could be due to differences in body position e.g., trunk/hip angle during exercise.

Purpose

We asked whether OLV differed between maximal running and cycling and if this difference was due to trunk/hip angle during exercise.

Methods

Eighteen men performed three graded maximal exercise tests; one while running, one while cycling in the drop position (i.e., extreme hip flexion), and one while cycling upright (i.e., seated with thorax upright). Resting flow-volume characteristics were measured in each body position to be used during exercise. Tidal flow-volume loops were measured throughout the exercise.

Results

V _E during maximal running (148.8 ± 18.9 L min^?1) tended to be lower than during cycling in the drop position (158.5 ± 24.7 L min^?1; p = 0.07) and in the upright position (158.5 ± 23.7 L min^?1; p = 0.06). End-inspiratory and end-expiratory lung volumes (EILV, EELV) were significantly larger during drop cycling compared to running (87.1 ± 4.1 and 35.8 ± 6.2 vs. 83.9 ± 6.0 and 33.0 ± 5.7 % FVC), but only EILV was larger during upright cycling compared to running (88.2 ± 3.5 % FVC). OLV and V _E did not differ between cycling positions.

Conclusion

Since OLV are altered by exercise mode, but cycling position did not have a significant impact on OLV, we conclude that trunk/hip angle is likely not the primary factor determining OLV during maximal exercise.     

Protein ingestion does not impair exercise-induced AMPK signalling when in a glycogen-depleted state: implications for train-low compete-high

The aim of the present study was to test the hypothesis that consuming protein does not attenuate AMPK signalling when exercise is commenced in a glycogen-depleted state. After performing a glycogen-depleting protocol the evening before, the subsequent morning ten active men performed 45 min steady-state cycling at 50 % of peak power output (PPO) followed by an exercise capacity test (1-min intervals at 80 % PPO interspersed with 1-min periods at 40 % PPO). In a repeated measures design, subjects consumed 20 g of a casein hydrolysate solution (PRO) 45 min before exercise, 10 g during and a further 20 g immediately post-exercise, or an equivalent volume of a non-calorie taste matched placebo (PLA). Resting (PRO = 134 ± 29; PLA = 136 ± 28 mmol kg^?1) and post-exercise muscle glycogen (PRO = 43 ± 16; PLA = 47 ± 18 mmol kg^?1) was not different (P > 0.05) between trials nor was exercise capacity (PRO = 26 ± 9; PLA = 25 ± 10 min, P > 0.05). Phosphorylation of AMPK^Thr172 increased threefold immediately post-exercise (P < 0.05) and PGC1?mRNA increased sixfold at 3 h post-exercise (P < 0.05), though there were no differences between conditions (P > 0.05). In contrast, there was a trend (P = 0.08) for a divergent response in eEF2^Thr56 phosphorylation such that 1.5 fold increases post- and 3 h post-exercise in PLA were blunted with PRO, thus indicative of greater eEF2 activation. We conclude that athletes who deliberately incorporate training phases with reduced muscle glycogen into their training programmes may consume protein before, during and after exercise without negating signalling through the AMPK cascade.     

Exercise does not increase cyclooxygenase-2 myocardial levels in young or senescent hearts

Increased myocardial cyclooxygenase-2 (COX-2) activity is essential for late phase ischemic preconditioning (IPC). Currently unknown is whether cardioprotection elicited by exercise also involves elevated myocardial COX-2 activity. This investigation tested whether aerobic exercise elevates myocardial COX-2 protein content or enzyme activity in young and senescent male Fisher 344 rats assigned to sedentary or cardioprotective endurance exercise treatments (3 consecutive days of treadmill exercise, 60 min/day @~70% VO₂max). Assay of cardiac COX-2 protein content, catalytic activity, and inducible nitric oxide synthase (iNOS) protein content reveal that exercise did not alter COX-2 activity (PGE₂, p = 0.866; PGF1α, p = 0.796) or protein levels (p = 0.397) within young or senescent hearts. In contrast, myocardial iNOS, an up-stream mediator of COX-2 expression, was over-expressed by an average of 37% in aged hearts (p = 0.005), though iNOS was not influenced by exercise. Findings reveal exercise does not elevate cardiac COX-2 activity and suggests that mechanisms responsible for cardioprotection differ between IPC and aerobic exercise.     

Do greater rates of body heat storage precede the accelerated reduction of self-paced exercise intensity in the heat?

Aim

To reevaluate the previous hypothesis that greater reductions in self-paced exercise intensity in the heat are mediated by early differences in the rate of body heat storage (S).

Methods

Eight trained volunteers cycled in 19 °C/1.8 kPa (COOL), 25 °C/1.2 kPa (NORM), and 34 °C/1.6 kPa (HOT), while maintaining an RPE of 16. Potential differences in S following the onset of exercise were assessed by comparing rates of esophageal temperature change (ΔT _es/Δt); and estimated S values using a traditional two-compartment thermometric model (S _therm) of changes in rectal (T _re) and skin (T _sk) temperature, and partitional calorimetry (S _cal).

Results

After 15 min of exercise, workload decreased more in HOT vs. COOL (P = 0.03), resulting in a shorter time (HOT: 40.7 ± 14.9 min; COOL: 53.5 ± 18.7 min; P = 0.04) to 70 % of initial workload. However, there were no preceding differences in ΔT _es/Δt between conditions (P = 0.18). S _therm values were different between HOT and COOL during the first 5 min of exercise (P < 0.05), primarily due to negative S _therm values (?32 ± 15 kJ min^?1) in COOL, which according to partitional calorimetric measurements, required improbably high (~56 kJ min^?1) rates of evaporation when no sweating on the back and thigh was observed until after 7.6 ± 1.5 min and 4.8 ± 1.7 min of exercise, respectively. S _cal values in the first 5 min of exercise confirmed S was actually positive in COOL (+21 ± 8 kJ min^?1) and not negative. Different S _therm values following the onset of exercise at different environmental temperatures are simply due to transient differences in the rate of change in T _sk.

Conclusion

Reductions in self-paced exercise intensity in the heat are not mediated by early differences in S following the onset of exercise.     

Combining heat stress and moderate hypoxia reduces cycling time to exhaustion without modifying neuromuscular fatigue characteristics

Purpose

This study investigated the isolated and combined effects of heat [temperate (22 °C/30 % rH) vs. hot (35 °C/40 % rH)] and hypoxia [sea level (FiO₂ 0.21) vs. moderate altitude (FiO₂ 0.15)] on exercise capacity and neuromuscular fatigue characteristics.

Methods

Eleven physically active subjects cycled to exhaustion at constant workload (66 % of the power output associated with their maximal oxygen uptake in temperate conditions) in four different environmental conditions [temperate/sea level (control), hot/sea level (hot), temperate/moderate altitude (hypoxia) and hot/moderate altitude (hot + hypoxia)]. Torque and electromyography (EMG) responses following electrical stimulation of the tibial nerve (plantar-flexion; soleus) were recorded before and 5 min after exercise.

Results

Time to exhaustion was reduced (P < 0.05) in hot (?35 ± 15 %) or hypoxia (?36 ± 14 %) compared to control (61 ± 28 min), while hot + hypoxia (?51 ± 20 %) further compromised exercise capacity (P < 0.05). However, the effect of temperature or altitude on end-exercise core temperature (P = 0.089 and P = 0.070, respectively) and rating of perceived exertion (P > 0.05) did not reach significance. Maximal voluntary contraction torque, voluntary activation (twitch interpolation) and peak twitch torque decreased from pre- to post-exercise (?9 ± 1, ?4 ± 1 and ?6 ± 1 % all trials compounded, respectively; P < 0.05), with no effect of the temperature or altitude. M-wave amplitude and root mean square activity were reduced (P < 0.05) in hot compared to temperate conditions, while normalized maximal EMG activity did not change. Altitude had no effect on any measured parameters.

Conclusion

Moderate hypoxia in combination with heat stress reduces cycling time to exhaustion without modifying neuromuscular fatigue characteristics. Impaired oxygen delivery or increased cardiovascular strain, increasing relative exercise intensity, may have also contributed to earlier exercise cessation.     

Acute hypoxic exercise does not alter post-exercise iron metabolism in moderately trained endurance athletes

Purpose

This study measured the influence of acute hypoxic exercise on Interleukin-6 (IL-6), hepcidin, and iron biomarkers in athletes.

Methods

In a repeated measures design, 13 moderately trained endurance athletes performed 5 × 4 min intervals at 90 % of their peak oxygen consumption velocity (vVO_2peak) in both normoxic [NORM, fraction of inspired oxygen (F _IO₂) = 0.2093, 15.3 ± 1.7 km h^?1] and simulated hypoxic (HYP, F _IO₂ = 0.1450, 13.2 ± 1.5 km h^?1) conditions. Venous blood samples were obtained pre-, post-, and 3 h post-exercise, and analysed for serum hepcidin, IL-6, ferritin, iron, soluble transferrin receptor (sTfR), and transferrin saturation.

Results

Peak heart rate was significantly lower in HYP compared with NORM (p = 0.01); however, the rating of perceived exertion was similar between trials (p = 0.24). Ferritin (p = 0.02), transferrin (p = 0.03), and IL-6 (p = 0.01) significantly increased immediately post-exercise in both conditions, but returned to baseline 3 h later. Hepcidin levels significantly increased in both conditions 3 h post-exercise (p = 0.05), with no significant differences between trials. A significant treatment effect was observed between trials for sTfR (p = 0.01), but not iron and transferrin saturation.

Conclusion

Acute exercise in hypoxia did not influence post-exercise IL-6 production, hepcidin activity or iron metabolism compared with exercise at the same relative intensity in normoxia. Hence, acute exercise performed at the same relative intensity in hypoxia poses no further risk to an athlete’s iron status, as compared with exercise in normoxia.     

Cytokine response to acute running in recreationally-active and endurance-trained men

To compare the cytokine response to exhaustive running in recreationally-active (RA) and endurance-trained (ET) men. Eleven RA men (VO_2max 55 ± 7 mL·min^?1·kg^?1) and 10 ET men (VO_2max 68 ± 7 mL·min^?1·kg^?1) followed a controlled diet and refrained from volitional exercise for 8 days. On the fourth day, participants completed 60 min of treadmill running (65 % VO_2max), followed by intermittent running to exhaustion (70 % VO_2max). Fasting blood was obtained at baseline, after 20, 40 and 60 min of exercise, at the end of intermittent exercise, during 2 h of recovery and on four follow-up days (FU1–FU4). Tumour necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1ra) and creatine kinase (CK) were measured. Exercise increased the concentrations of all cytokines and CK, but there were no significant differences between groups. IL-1β increased (2.2–2.5-fold, P < 0.001) during exercise, while TNF-α was increased (1.6–2.0-fold, P < 0.001) during exercise and for 2 h post-exercise. IL-6 (71–84-fold, P < 0.001) and IL-1ra (52–64-fold, P < 0.001) were increased throughout exercise and up to FU1, peaking immediately after exercise and at 1.5–2 h post-exercise, respectively. CK concentrations were increased (P < 0.001) throughout exercise and up to FU4, peaking at FU1, but were not associated with changes in any cytokines. Exhaustive running resulted in modest and transient increases in TNF-α and IL-1β, and more marked and prolonged increases in IL-6 and IL-1ra, but improved training status did not affect this response. Increased CK might indicate either exercise-induced muscle cell disruption or increased cell permeability, although neither appears to have contributed to the increased cytokine concentrations.     

Exercise-induced muscle damage from bench press exercise impairs arm cranking endurance performance

The effects of exercise-induced muscle damage (EIMD) on the physiological, metabolic and perceptual responses during upper body arm cranking exercise are unknown. Nine physically active male participants performed 6 min of arm cranking exercise at ventilatory threshold (VT), followed by a time to exhaustion (TTE) trial at a workload corresponding to 80 % of the difference between VT and $ \dot V{\text{O}}_ {2{\rm peak}} $ 48 h after bench pressing exercise (10 × 6 repetitions at 70 % one repetition maximum) or 20 min sitting (control). Reductions in isokinetic strength and increased muscle soreness of the elbow flexors and extensors were evident at 24 and 48 h after bench pressing exercise (P < 0.05). Despite no change in $ \dot V{\text{O}}_2 $ , $ \dot V_{\text{E}} $ , HR and blood lactate concentration ([Bla]) between conditions (P > 0.05), rating of perceived exertion (RPE) was higher during the 6 min arm cranking after bench pressing exercise compared to the control condition (P < 0.05). TTE was reduced in the treatment condition (207.2 ± 91.9 cf. 293.4 ± 75.6 s; P < 0.05), as were end $ \dot V{\text{O}}_2 $ (P < 0.05) and [Bla] at 0, 5 and 10 min after exercise (P < 0.05). RPE during the TTE trial was higher after bench pressing (P < 0.05), although end RPE was not different between conditions (P > 0.05). This study provides evidence that EIMD caused by bench pressing exercise increases the sense of effort during arm cranking exercise that leads to a reduced exercise tolerance. The findings have implications for individuals participating in concurrent endurance and resistance training of the upper body.     

Low-volume,high-intensity,aerobic interval exercise for sedentary adults: \dot{V}O2max,cardiac mass,and heart rate recovery

Purpose

The aim of this study was to compare the effects of low-volume, high-intensity aerobic interval training (HAIT) on maximal oxygen consumption ( \(\dot{V}\) O_2max), left ventricular (LV) mass, and heart rate recovery (HRR) with high-volume, moderate-intensity continuous aerobic training (CAT) in sedentary adults.

Methods

Twenty-four healthy but sedentary male adults (aged 29.2 ± 7.2 years) participated in an 8-week, 3-day a week, supervised exercise intervention. They were randomly assigned to either HAIT (18 min, 180 kcal per exercise session) or CAT (45 min, 360 kcal). \(\dot{V}\) O_2max, LV mass (3T-MRI), and HRR at 1 min (HRR-1) and 2 min (HRR-2) after maximal exercise were measured pre- and post-intervention.

Results

Changes in \(\dot{V}\) O_2max during the 8-week intervention were significant (P < 0.01) in both groups (HAIT, 8.7 ± 3.2 ml kg^?1 min^?1, 22.4 ± 8.9 %; CAT, 5.5 ± 2.8 ml kg^?1 min^?1, 14.7 ± 9.5 %), while the \(\dot{V}\) O_2max improvement in HAIT was greater (P = 0.02) than in CAT. LV mass in HAIT increased (5.1 ± 8.4 g, 5.7 ± 9.1 %, P = 0.05), but not in CAT (0.9 ± 7.8 g, 1.1 ± 8.4 %, P = 0.71). While changes in HRR-1 were not significant in either group, change in HRR-2 for HAIT (9.5 ± 6.4 bpm, 19.0 ± 16.0 %, P < 0.01) was greater (P = 0.03) than for CAT (1.6 ± 10.9 bpm, 3.9 ± 16.2 %, P = 0.42).

Conclusions

This study suggests that HAIT has potential as a time-efficient training mode to improve cardiorespiratory capacity and autonomic nervous system function in sedentary adults.     

Low level laser therapy before eccentric exercise reduces muscle damage markers in humans

The purpose of the present study was to determine the effect of low level laser therapy (LLLT) treatment before knee extensor eccentric exercise on indirect markers of muscle damage. Thirty-six healthy men were randomized in LLLT group (n = 18) and placebo group (n = 18). After LLLT or placebo treatment, subjects performed 75 maximal knee extensors eccentric contractions (five sets of 15 repetitions; velocity = 60° seg^?1; range of motion = 60°). Muscle soreness (visual analogue scale—VAS), lactate dehydrogenase (LDH) and creatine kinase (CK) levels were measured prior to exercise, and 24 and 48 h after exercise. Muscle function (maximal voluntary contraction—MVC) was measured before exercise, immediately after, and 24 and 48 h post-exercise. Groups had no difference on kineanthropometric characteristics and on eccentric exercise performance. They also presented similar baseline values of VAS (0.00 mm for LLLT and placebo groups), LDH (LLLT = 186 IU/l; placebo = 183 IU/l), CK (LLLT = 145 IU/l; placebo = 155 IU/l) and MVC (LLLT = 293 Nm; placebo = 284 Nm). VAS data did not show group by time interaction (P = 0.066). In the other outcomes, LLLT group presented (1) smaller increase on LDH values 48 h post-exercise (LLLT = 366 IU/l; placebo = 484 IU/l; P = 0.017); (2) smaller increase on CK values 24 h (LLLT = 272 IU/l; placebo = 498 IU/l; P = 0.020) and 48 h (LLLT = 436 IU/l; placebo = 1328 IU/l; P < 0.001) post-exercise; (3) smaller decrease on MVC immediately after exercise (LLLT = 189 Nm; placebo = 154 Nm; P = 0.011), and 24 h (LLLT = 249 Nm; placebo = 205 Nm; P = 0.004) and 48 h (LLLT = 267 Nm; placebo = 216 Nm; P = 0.001) post-exercise compared with the placebo group. In conclusion, LLLT treatment before eccentric exercise was effective in terms of attenuating the increase of muscle proteins in the blood serum and the decrease in muscle force.     

Successive bouts of cycling stimulates genes associated with mitochondrial biogenesis

Exercise increases mRNA for genes involved in mitochondrial biogenesis and oxidative enzyme capacity. However, little is known about how these genes respond to consecutive bouts of prolonged exercise. We examined the effects of 3 h of intensive cycling performed on three consecutive days on the mRNA associated with mitochondrial biogenesis in trained human subjects. Forty trained cyclists were tested for VO_2max (54.7 ± 1.1 ml kg^?1 min^?1). The subjects cycled at 57% watts_max for 3 h using their own bicycles on CompuTrainer? Pro Model trainers (RacerMate, Seattle, WA) on three consecutive days. Muscle biopsies were obtained from the vastus lateralis pre- and post-exercise on days one and three. Muscle samples were analyzed for mRNA content of peroxisome proliferator receptor gamma coactivator-1 alpha (PGC-1α), sirtuin 1 (Sirt-1), cytochrome c, and citrate synthase. Data were analyzed using a 2 (time) × 2 (day) repeated measures ANOVA. Of the mRNA analyzed, the following increased from pre to post 3 h rides: cytochrome c (P = 0.006), citrate synthase (P = 0.03), PGC-1α (P < 0.001), and Sirt-1 (P = 0.005). The following mRNA showed significant effects from days one to three: cytochrome c (P < 0.001) and citrate synthase (P = 0.01). These data show that exhaustive cycling performed on three consecutive days resulted in both acute and chronic stimuli for mRNA associated with mitochondrial biogenesis in already trained subjects. This is the first study to illustrate an increase in sirtuin-1 mRNA with acute and chronic exercise. These data contribute to the understanding of mRNA expression during both acute and successive bouts of prolonged exercise.