Both flow-mediated vasodilation procedures and acute exercise improve endothelial function in obese young men

Obesity is associated with impaired endothelial function assessed as flow-mediated vasodilation (FMD), the procedure of which involves transient brachial artery occlusion and following reactive hyperemia. Acute aerobic exercise can improve FMD. This study examined the effects of repeated FMD procedures and acute aerobic exercise on FMD in obese young men. Upper arm cuff inflation of 200 mmHg for 5 min and subsequent deflation was induced at 0, 1 and 2 h to examine effects of repeated FMD procedures on FMD in obese subjects, as well as in lean controls. To observe the combined effects of FMD procedures and acute exercise on FMD in obese subjects, 45 min moderate exercise was performed immediately after FMD procedure at 0 h, with the procedure repeated at 1 and 2 h. The results showed that, after repeated FMD procedures, FMD in obese subjects increased from 5.9 ± 4.0% to 6.5 ± 3.2% and 8.4 ± 2.8% (P = 0.017), whereas FMD demonstrated no changes in lean controls (P = 0.90). After repeated FMD procedures and exercise, FMD in the obese subjects increased from 7.3 ± 3.5% to 9.5 ± 4.0% and 11.0 ± 4.3% (P = 0.0004). The present findings demonstrate that both repeated FMD procedures and acute aerobic exercise improve FMD in obese subjects.     

Creatine supplementation attenuates hemodynamic and arterial stiffness responses following an acute bout of isokinetic exercise

Arterial stiffness and hemodynamics may be increased following a bout of resistance exercise. Oral creatine supplementation (Cr) may attenuate cardiovascular responses after exercise via improved anaerobic metabolism. This study was aimed to determine the effect of Cr on hemodynamic and arterial stiffness responses after acute isokinetic exercise. Sixteen healthy males (22.6 ± 0.6 year) were randomly assigned to either placebo (Pl, n = 8) or Cr (n = 8) (2 × 5 g/day) for 3 weeks. Brachial systolic blood pressure (SBP), heart rate (HR), brachial-ankle pulse wave velocity (baPWV), and leg PWV were measured in the supine position at rest before and after the interventions. After the supplementation period, parameters were also measured 5 min (PE5) and 15 min (PE15) after two sets of leg isokinetic exercise. There was no difference between the groups in resting measurements before and after the supplementation. Compared with the Pl group, the Cr group had attenuated (P < 0.05) increases in SBP at PE5 (Pl 14.0 ± 2.5, Cr 5.6 ± 2.3 mmHg), HR at both P5 (Pl 28 ± 4 vs. Cr 16 ± 2 beats/min) and PE15 (Pl 21 ± 3, Cr 11 ± 2 beats/min) and rate pressure product at P5 (Pl 45.8 ± 6.4, Cr 24.8 ± 2.2) and P15 (Pl 34.2 ± 5.0, Cr 15.9 ± 6.0). Compared with the Pl group, the Cr group had suppressed increases in baPWV at PE5 (Pl 1.5 ± 0.4, Cr −0.1 ± 0.4 m/s) and PE15 (Pl 1.1 ± 0.2, Cr −0.3 ± 0.3 m/s) and returned SBP to pre-exercise values at PE15 (Pl 10.6 ± 2.8, Cr 2.1 ± 2.6 mmHg). PWV in the exercised leg decreased at PE5 in both groups. These findings suggest that Cr supplementation attenuates the hemodynamic and baPWV responses after acute isokinetic exercise.     

Lower limb compression garment improves recovery from exercise-induced muscle damage in young, active females

This study aimed to investigate the efficacy of lower limb compression as a recovery strategy following exercise-induced muscle damage (EIMD). Seventeen female volunteers completed 10 × 10 plyometric drop jumps from a 0.6-m box to induce muscle damage. Participants were randomly allocated to a passive recovery (n = 9) or a compression treatment (n = 8) group. Treatment group volunteers wore full leg compression stockings for 12 h immediately following damaging exercise. Passive recovery group participants had no intervention. Indirect indices of muscle damage (muscle soreness, creatine kinase activity, knee extensor concentric strength, and vertical jump performance) were assessed prior to and 1, 24, 48, 72, and 96 h following plyometric exercise. Plyometric exercise had a significant effect (p ≤ 0.05) on all indices of muscle damage. The compression treatment reduced decrements in countermovement jump performance (passive recovery 88.1 ± 2.8% vs. treatment 95.2 ± 2.9% of pre-exercise), squat jump performance (82.3 ± 1.9% vs. 94.5 ± 2%), and knee extensor strength loss (81.6 ± 3% vs. 93 ± 3.2%), and reduced muscle soreness (4.0 ± 0.23 vs. 2.4 ± 0.24), but had no significant effect on creatine kinase activity. The results indicate that compression clothing is an effective recovery strategy following exercise-induced muscle damage.     

The exercise dose affects oxidative stress and brachial artery flow-mediated dilation in trained men

The aim of this investigation was to establish whether changes in oxidative stress and endothelial function following acute aerobic exercise are dose-dependent. Ten healthy trained men completed four exercise sessions: 50% VO_2peak for 30 min (moderate intensity moderate duration, MIMD), 50% VO_2peak for 60 min (moderate intensity long duration, MILD), 80% VO_2peak for 30 min (high intensity moderate duration, HIMD), and 80% VO_2peak for the time to reach the caloric equivalent of MIMD (high intensity short duration, HISD). Thiobarbituric acid reactive substances (TBARS) were measured as an index of oxidative stress and brachial artery flow-mediated dilation (FMD) was assessed as an index of endothelial function. Variables were measured at baseline, immediately post-exercise, 1 and 2 h post-exercise. Both HIMD (14.2 ± 2.5 μmol/L) and HISD (14.7 ± 1.9 μmol/L) TBARS differed from MIMD (11.8 ± 1.5 μmol/L) immediately post-exercise. TBARS increased from pre to immediately post-exercise for HIMD (12.6 ± 2.1 vs.14.2 ± 2.5 μmol/L) and HISD (12.3 ± 2.8 vs. 14.7 ± 1.9 μmol/L). Both MIMD (7.2 ± 2.2%) and HISD (7.6 ± 2.7%) FMD immediately post-exercise were greater than HIMD (4.7 ± 2.2%). An increase of FMD from pre to immediately post-exercise was found for MIMD (5.0 ± 2.5 vs. 7.2 ± 2.2%) and HISD (5.9 ± 2.4 vs. 7.6 ± 2.7%). These data suggest that acute exercise-induced TBARS are exercise intensity-dependent whereas FMD appears to improve following energy expenditure equivalent to 30 min 50% VO_2peak, regardless of intensity or duration.     

<Emphasis Type="Italic">V</Emphasis>O<Subscript>2</Subscript>max during successive maximal efforts

The concept of VO₂max has been a defining paradigm in exercise physiology for >75 years. Within the last decade, this concept has been both challenged and defended. The purpose of this study was to test the concept of VO₂max by comparing VO₂ during a second exercise bout following a preliminary maximal effort exercise bout. The study had two parts. In Study #1, physically active non-athletes performed incremental cycle exercise. After 1-min recovery, a second bout was performed at a higher power output. In Study #2, competitive runners performed incremental treadmill exercise and, after 3-min recovery, a second bout at a higher speed. In Study #1 the highest VO₂ (bout 1 vs. bout 2) was not significantly different (3.95 ± 0.75 vs. 4.06 ± 0.75 l min⁻¹). Maximal heart rate was not different (179 ± 14 vs. 180 ± 13 bpm) although maximal V _E was higher in the second bout (141 ± 36 vs. 151 ± 34 l min⁻¹). In Study #2 the highest VO₂ (bout 1 vs. bout 2) was not significantly different (4.09 ± 0.97 vs. 4.03 ± 1.16 l min⁻¹), nor was maximal heart rate (184 + 6 vs. 181 ± 10 bpm) or maximal V _E (126 ± 29 vs. 126 ± 34 l min⁻¹). The results support the concept that the highest VO₂ during a maximal incremental exercise bout is unlikely to change during a subsequent exercise bout, despite higher muscular power output. As such, the results support the “classical” view of VO₂max.     

Levels of serum creatine kinase and myoglobin in women after two isometric exercise conditions

Summary The purpose of this study was to measure serum creatine kinase (CK) activity and serum myoglobin (MG) concentrations in women after two unilateral isometric knee extension exercises. Forty maximal voluntary contractions (MVC) were held for 10 s, with either a 5 s (10∶5) or 20 s 10∶20 exercise (349.4±66.1 mU · ml⁻¹) and 6 h and MG values were measured pre, 0, 3, 6, and 18 h post exercise. For CK, the highest post exercise values were observed at 6 h following the 10∶20 exercise (349.4±66.1 mU · ml⁻¹) and 6 h following the 10∶5 exercise (194.1±18.6 mU · ml⁻¹). For MG, the highest values were found 3 h after the 10∶20 exercise (148.9±61.7 ng · ml⁻¹) and 6 h after the 10∶5 exercise (67.3±10.9 ng · ml⁻¹). Serum CK and MG levels were significantly greater (p<0.01) after the 10∶20 exercise bout. The data demonstrate that CK and MG values for women increase significantly after isometric exercise. Since greater tension levels were maintained during the 10∶20 exercise it is hypothesized that increased serum CK and MG values after isometric exercise may be related to the tension generated by the contracting muscle.     

Effect of prior exercise on postprandial lipemia and markers of inflammation and endothelial activation in normal weight and overweight adolescent boys

Postprandial lipemia (PPL) is associated with impaired endothelial function and inflammation. Acute exercise reduces PPL in adults. This investigation examined the effect of an acute bout of exercise on postprandial changes in triglycerides (TG), glucose, insulin, inflammation [white blood cell count (WBC), interleukin-6 (IL-6) tumor necrosis factor-alpha, C-reactive protein (CRP)] and endothelial activation [soluble intercellular adhesion molecule-1 (sICAM-1), vascular adhesion molecule-1 (sVCAM-1)] following a high-fat meal in adolescents. Ten normal weight (NW) (BMI, 20.9 ± 1.7 kg m⁻²; 15.6 ± 0.7 years) and eight overweight (OW) (BMI, 28.3 ± 3.6 kg m⁻²; 15.9 ± 0.4 years) adolescent boys underwent two 6-h oral fat tolerance tests (OFTT) separated by 7–10 days. On the evening prior to each OFTT, subjects either rested or completed a treadmill exercise bout (65% 600 kcal expended). Exercise reduced (P < 0.01) the postprandial TG area under the curve by ~20% in the NW and OW groups. The postprandial glucose and insulin response did not differ between the control and exercise trials or between the NW and OW groups. Circulating leukocytes and plasma IL-6 levels increased (P < 0.01) in the NW and OW groups 6 h following the OFTT in both experimental conditions. There were no changes in CRP, sVCAM-1 or sICAM-1 following the OFTT and there were no differences between experimental condition or NW and OW groups. In conclusion, a moderate exercise bout prior to a high-fat meal effectively reduces postprandial TG concentrations to a similar degree in both NW and OW adolescents, but does not reduce the concomitant postprandial increase in WBC or IL-6.     

Exercise-induced muscle damage and the repeated bout effect: evidence for cross transfer

We examined whether a prior bout of eccentric exercise in the elbow flexors provided protection against exercise-induced muscle damage in the contralateral arm. Fifteen males (age 22.7 ± 2.1 years; height 178.6 ± 6.8 cm, mass 75.8 ± 9.3 kg) were randomly assigned to two groups who performed two bouts of 60 eccentric contractions (30°/s) separated by 2 weeks: ipsilateral (n = 7, both bouts performed in the same arm), contralateral (n = 8, one bout performed in each arm). Strength, muscle soreness and resting arm angle (RAA) were measured at baseline and at 1, 24 and 48 h post exercise. Surface electromyography was recorded during both bouts of exercise. The degree of strength loss was attenuated (p < 0.05) in the ipsilateral group after the second bout of eccentric exercise (−22 cf. −3% for bout 1 and 2 at 24 h, respectively). Strength loss following eccentric exercise was also attenuated (p < 0.05) at 24 h in the contralateral group (−30 cf. 13% for bout 1 and 2, respectively). Muscle soreness (≈34 cf 19 mm) and change in RAA (≈5 cf. 3%) were also lower following the second bout of eccentric exercise (p < 0.05), although there was no difference in the overall change in these values between groups. Median frequency (MF) was decreased by 31% between bouts, with no difference between groups. Data support observations that the repeated bout effect transfers to the opposite (untrained) limb. The similar reduction in MF between bouts for the two groups provides evidence for a centrally mediated, neural adaptation.     

The repeated bout effect of eccentric exercise is not associated with changes in voluntary activation

The aim of this study was to compare the possible changes in muscle activation level between a first and second bout of damaging eccentric exercise performed at 2 weeks interval (i.e. repeated bout effect). To that purpose, ten physically active males took part in this study. The eccentric exercise consisted of 10 sets of 12 maximal voluntary contractions (MVC) produced by the knee extensors during movements performed at a constant speed of 160°s⁻¹. Changes in voluntary and electrically evoked torque in concentric and/or isometric conditions were assessed at the following time points: pre-exercise, and 2 min, 1 and 24 h after each eccentric exercise. At the same time points, voluntary activation was quantified by the superimposed electrical stimulation technique. Muscle soreness and plasma CK activity were measured within 48 h after the eccentric exercise. The results showed that the decrease in eccentric peak torque was linear throughout the exercise protocol. At the end of bouts 1 and 2, torque was significantly reduced by 27.7 ± 9.1 and 23.4 ± 11.2, respectively, with no difference between bouts (P > 0.05). At 24 h post-exercise, a lower reduction (P < 0.05) in MVC (17.8 ± 5.4%) and electrically evoked (16.7 ± 4.6%) isometric torque was observed for bout 2. In contrast, no statistical difference was found in the deficit in voluntary activation between the two bouts. In conclusion, our results indicate that the repeated bout effect of eccentric exercise appears to reduce muscle damage, but does not influence the level of voluntary activation.     

One-set resistance training elevates energy expenditure for 72 h similar to three sets

To compare the effects of an acute one versus three-set full body resistance training (RT) bout in eight overweight (mean ± SD, BMI = 25.6 ± 1.5 kg m⁻²) young (21.0 ± 1.5 years) adults on resting energy expenditure (REE) measured on four consecutive mornings following each protocol. Participants performed a single one-set or three-set whole body (10 exercises, 10 repetition maximum) RT bout following the American College of Sports Medicine (ACSM) guidelines for RT. REE and respiratory exchange ratio (RER) by indirect calorimetry were measured at baseline and at 24, 48, and 72 h after the RT bout. Participants performed each protocol in randomized, counterbalanced order separated by 7 days. There was no difference between protocols for REE or RER. However, REE was significantly (p < 0.05) elevated (~5% or ~400 kJ day⁻¹) in both the protocols at 24, 48, and 72 h post RT bout compared with baseline. There was a no change in RER in both the protocols at 72 h compared to baseline. A one-set RT bout following the ACSM guidelines for RT and requiring only ~15 min to complete was as effective as a three-set RT bout (~35 min to complete) in elevating REE for up to 72 h post RT in overweight college males, a group at high risk of developing obesity. The one-set RT protocol may provide an attractive alternative to either aerobic exercise or multiple-set RT programs for weight management in young adults, due to the minimal time commitment and the elevation in REE post RT bout.     

Post-exercise protein synthesis rates are only marginally higher in type I compared with type II muscle fibres following resistance-type exercise

We examined the effect of an acute bout of resistance exercise on fractional muscle protein synthesis rates in human type I and type II muscle fibres. After a standardised breakfast (31 ± 1 kJ kg⁻¹ body weight, consisting of 52 Energy% (En%) carbohydrate, 34 En% protein and 14 En% fat), 9 untrained men completed a lower-limb resistance exercise bout (8 sets of 10 repetitions leg press and leg extension at 70% 1RM). A primed, continuous infusion of l-[ring-¹³C₆]phenylalanine was combined with muscle biopsies collected from both legs immediately after exercise and after 6 h of post-exercise recovery. Single muscle fibres were dissected from freeze-dried biopsies and stained for ATPase activity with pre-incubation at a pH of 4.3. Type I and II fibres were separated under a light microscope and analysed for protein-bound l-[ring-¹³C₆]phenylalanine labelling. Baseline (post-exercise) l-[ring-¹³C₆]phenylalanine muscle tissue labelling, expressed as (∂¹³C/¹²C), averaged −32.09 ± 0.28, −32.53 ± 0.10 and −32.02 ± 0.16 in the type I and II muscle fibres and mixed muscle, respectively (P = 0.14). During post-exercise recovery, muscle protein synthesis rates were marginally (8 ± 2%) higher in the type I than type II muscle fibres, at 0.100 ± 0.005 versus 0.094 ± 0.005%/h, respectively (P < 0.05), whereby rates of mixed muscle protein were 0.091 ± 0.005%/h. Muscle protein synthesis rates following resistance-type exercise are only marginally higher in type I compared with type II muscle fibres.     

Isometric handgrip exercise improves acute neurocardiac regulation

Isometric handgrip (IHG) training (>6 weeks) has been shown to reduce resting arterial blood pressure (ABP) and improve cardiac autonomic modulation. However, the effects of a single bout of IHG on acute neurocardiac regulation remain unknown. The purpose of this study was to examine the effect of IHG exercise on nonlinear heart rate dynamics and cardiac vagal activity. Nonlinear dynamics were assessed by sample entropy, detrended fluctuation analysis (α₁), and correlation dimension techniques. The 4-second exercise test was used to calculate the cardiac vagal index (CVI), an indirect measure of cardiac vagal activity. In a randomized crossover design, 18 older (70 ± 5 years of age) subjects completed IHG exercise (four 2-min isometric contractions at 30% MVC) and a time-matched control condition. Following a single bout of bilateral IHG, there was a small reduction in systolic blood pressure (125 ± 2 to 122 ± 1 mmHg, P < 0.01), in addition to, a significant decrease in α₁ (1.42 ± 0.12 to 1.22 ± 0.10, P < 0.05), an increase in sample entropy (1.28 ± 0.03 to 1.40 ± 0.05, P < 0.001), and an increase in the CVI (1.24 ± 0.03 to 1.29 ± 0.03, P < 0.01). These results suggest improvements in acute cardiac autonomic modulation following a single bout of IHG. This may be mechanistically linked to the observed reductions in ABP seen in previous IHG training studies. Alternatively, these acute effects may have clinical applications and require further investigation.     

Creatine supplementation prevents acute strength loss induced by concurrent exercise

Purpose

To investigate the effect of creatine (CR) supplementation on the acute interference induced by aerobic exercise on subsequent maximum dynamic strength (1RM) and strength endurance (SE, total number of repetitions) performance.

Methods

Thirty-two recreationally strength-trained men were submitted to a graded exercise test to determine maximal oxygen consumption (VO_2max: 41.56 ± 5.24 ml kg^?1 min^?1), anaerobic threshold velocity (AT_v: 8.3 ± 1.18 km h^?1), and baseline performance (control) on the 1RM and SE (4 × 80 % 1RM to failure) tests. After the control tests, participants were randomly assigned to either a CR (20 g day^?1 for 7 days followed by 5 g day^?1 throughout the study) or a placebo (PL-dextrose) group, and then completed 4 experimental sessions, consisting of a 5-km run on a treadmill either continuously (90 % AT_v) or intermittently (1:1 min at vVO_2max) followed by either a leg- or bench-press SE/1RM test.

Results

CR was able to maintain the leg-press SE performance after the intermittent aerobic exercise when compared with C (p > 0.05). On the other hand, the PL group showed a significant decrease in leg-press SE (p ≤ 0.05). CR supplementation significantly increased bench-press SE after both aerobic exercise modes, while the bench-press SE was not affected by either mode of aerobic exercise in the PL group. Although small increases in 1RM were observed after either continuous (bench press and leg press) or intermittent (bench press) aerobic exercise in the CR group, they were within the range of variability of the measurement. The PL group only maintained their 1RM.

Conclusions

In conclusion, the acute interference effect on strength performance observed in concurrent exercise may be counteracted by CR supplementation.     

Effects of aerobic exercise on urinary estrogens and progestagens in pre and postmenopausal women

The purpose of this study was to elucidate the effect of 6 months of aerobic exercise on urinary excretion of female steroid hormones in pre and postmenopausal women and to check the basal values of urinary steroid. To this end, 20 premenopausal (age 45.56 ± 4.06 years) and 20 postmenopausal (age 52.27 ± 3.80 years) women, all sedentary, were studied before and after a supervised 6-month exercise training program (at 60–70% of maximal heart rate, 60 min/day, 3 days/week), based on aerobic dance. The exercise included standing on one leg, squatting, walking, and touching their heels. Before and after the program, anthropometric data and VO_2max were measured and urine samples were collected and analyzed by gas chromatography/mass spectrometry (GC/Q-MS). Both, pre and postmenopausal women, improved their VO_2max after the aerobic exercise program. Regarding the urinary steroids, on the one hand, important differences were observed between urinary estrogens and progestagens in pre and postmenopausal women in basal values. Estrone (P < 0.05), pregnanediol (P < 0.01), pregnanetriol (P < 0.05), and estriol (P < 0.01) levels were lower in postmenopausal women than in premenopausal women. On the other hand, the aerobic exercise program did not affect postmenopausal women in the same way as premenopausal women. After the exercise program, no changes in urinary steroid levels were observed in premenopausal women. However, the aerobic exercise program caused an increase in urinary excretion of pregnanediol (P < 0.05) and pregnanetriol (P < 0.05) in postmenopausal women.     

The effect of acute aerobic exercise on pulse wave velocity and oxidative stress following postprandial hypertriglyceridemia in healthy men

Oxidative stress is postulated to be responsible for the postprandial impairments in vascular function. The purpose of this study was to measure pulse wave velocity (PWV) and markers of postprandial oxidative stress before and after an acute bout of moderate exercise. Ten trained male subjects (age 21.5 ± 2.5 years, VO₂ max 58.5 ± 7.1 ml kg⁻¹ min⁻¹) participated in a randomised crossover design: (1) high-fat meal alone (2) high-fat meal followed 2 h later by a bout of 1 h moderate (60% max HR) exercise. PWV was examined at baseline, 1, 2, 3, and 4 h postprandially. Blood Lipid hydroperoxides (LOOHs), Superoxide dismutase (SOD) and other biochemical markers were measured. PWV increased at 1 h (6.49 ± 2.1 m s⁻¹), 2 h (6.94 ± 2.4 m s⁻¹), 3 h (7.25 ± 2.1 m s⁻¹) and 4 h (7.41 ± 2.5 m s⁻¹) respectively, in the control trial (P < 0.05). There was no change in PWV at 3 h (5.36 ± 1.1 m s⁻¹) or 4 h (5.95 ± 2.3 m s⁻¹) post ingestion in the exercise trial (P > 0.05). LOOH levels decreased at 3 h post ingestion in the exercise trial compared to levels at 3 h (P < 0.05) in the control trial. SOD levels were lower at 3 h post ingestion in the control trial compared to 3 h in the exercise trial (0.52 ± 0.05 vs. 0.41 ± 0.1 units μl⁻¹; P < 0.05). These findings suggest that a single session of aerobic exercise can ameliorate the postprandial impairments in arterial function by possibly reducing oxidative stress levels.     

Acute effects of hyperglycaemia with and without exercise on endothelial function in healthy young men

Post-prandial hyperglycaemia impairs endothelial function as evaluated by brachial artery flow-mediated dilation (FMD). Exercise is an intervention to protect against cardiovascular disease and to improve FMD. In this study, we examined whether the effect of acute hyperglycaemia on endothelial function in healthy young men is restored by aerobic exercise. Using a counterbalanced, randomized crossover design, we measured the brachial artery FMD at baseline and 1, 2, 3 and 4 h after 75 g glucose ingestion in 11 healthy young men, with and without a single bout of aerobic exercise. Brachial artery FMD declined from 11.4 ± 3.8% at baseline to 7.3 ± 3.4% 1 h after oral glucose ingestion, and returned to baseline after 4 h. When the oral glucose ingestion was followed immediately by 45 min of treadmill exercise at an intensity of 60% maximal oxygen uptake, FMD demonstrated no significant decrease (11.8 ± 2.5, 11.3 ± 2.8, 12.2 ± 2.7, 13.5 ± 3.5, and 12.6 ± 2.4% at baseline and 4 h after ingestion, respectively). The results indicate that the aerobic exercise restores the impaired FMD induced by oral glucose ingestion.     

Does oxidative capacity affect energy cost? An in vivo MR investigation of skeletal muscle energetics

Investigations of training effects on exercise energy cost have yielded conflicting results. The purpose of the present study was to compare quadriceps energy cost and oxidative capacity between endurance-trained and sedentary subjects during a heavy dynamic knee extension exercise. We quantified the rates of ATP turnover from oxidative and anaerobic pathways with ³¹P-MRS, and we measured simultaneously pulmonary oxygen uptake in order to assess both total ATP production [i.e., energy cost (EC)] and O₂ consumption (O₂ cost) scaled to power output. Seven sedentary (SED) and seven endurance-trained (TRA) subjects performed a dynamic standardized rest-exercise-recovery protocol at an exercise intensity corresponding to 35% of maximal voluntary contraction. We showed that during a dynamic heavy exercise, the O₂ cost and EC were similar in the SED and endurance-trained groups. For a given EC, endurance-trained subjects exhibited a higher relative mitochondrial contribution to ATP production at the muscle level (84 ± 12% in TRA and 57 ± 12% in SED; P < 0.01) whereas the anaerobic contribution was reduced (18 ± 12% in TRA and 44 ± 11% in SED; P < 0.01). Our results obtained in vivo illustrate that on the one hand the beneficial effects of endurance training are not related to any reduction in EC or O₂ cost and on the other hand that this similar EC was linked to a change regarding the contribution of anaerobic and oxidative processes to energy production, i.e., a greater aerobic energy contribution associated with a concomitant reduction of the anaerobic energy supply.     

Short term effects of various water immersions on recovery from exhaustive intermittent exercise

In order to investigate the effectiveness of different techniques of water immersion recovery on maximal strength, power and the post-exercise inflammatory response in elite athletes, 41 highly trained (Football, Rugby, Volleyball) male subjects (age = 21.5 ± 4.6 years, mass = 73.1 ± 9.7 kg and height = 176.7 ± 9.7 cm) performed 20 min of exhaustive, intermittent exercise followed by a 15 min recovery intervention. The recovery intervention consisted of different water immersion techniques, including: temperate water immersion (36°C; TWI), cold water immersion (10°C; CWI), contrast water temperature (10–42°C; CWT) and a passive recovery (PAS). Performances during a maximal 30-s rowing test (P_30 s), a maximal vertical counter-movement jump (CMJ) and a maximal isometric voluntary contraction (MVC) of the knee extensor muscles were measured at rest (Pre-exercise), immediately after the exercise (Post-exercise), 1 h after (Post 1 h) and 24 h later (Post 24 h). Leukocyte profile and venous blood markers of muscle damage (creatine kinase (CK) and lactate dehydrogenase (LDH)) were also measured Pre-exercise, Post 1 h and Post 24 h. A significant time effect was observed to indicate a reduction in performance (Pre-exercise vs. Post-exercise) following the exercise bout in all conditions (P < 0.05). Indeed, at 1 h post exercise, a significant improvement in MVC and P_30 s was respectively observed in the CWI and CWT groups compared to pre-exercise. Further, for the CWI group, this result was associated with a comparative blunting of the rise in total number of leucocytes at 1 h post and of plasma concentration of CK at 24 h post. The results indicate that the practice of cold water immersion and contrast water therapy are more effective immersion modalities to promote a faster acute recovery of maximal anaerobic performances (MVC and 30″ all-out respectively) after an intermittent exhaustive exercise. These results may be explained by the suppression of plasma concentrations of markers of inflammation and damage, suggesting reduced passive leakage from disrupted skeletal muscle, which may result in the increase in force production during ensuing bouts of exercise.     

Oral creatine supplementation decreases plasma markers of adenine nucleotide degradation during a 1‐h cycle test

We investigated the effect of oral creatine supplementation (20 g d^?1 for 7 days) on metabolism during a 1‐h cycling performance trial. Twenty endurance‐trained cyclists participated in this double‐blind placebo controlled study. Five days after familiarization with the exercise test, the subjects underwent a baseline muscle biopsy. Thereafter, a cannula was inserted into a forearm vein before performing the baseline maximal 1‐h cycle (test 1 (T1)). Blood samples were drawn at regular intervals during exercise and recovery. After creatine (Cr) loading, the muscle biopsy, 1‐h cycling test (test 2 (T2)) and blood sampling were repeated. Resting muscle total creatine (TCr), measured by high performance liquid chromatography, was increased (P < 0.001) in the creatine group from 123.0 ± 3.8 ? 159.8 ± 7.9 mmol kg^?1 dry wt, but was unchanged in the placebo group (126.7 ± 4.7 ? 127.5 ± 3.6 mmol kg^?1 dry wt). The extent of Cr loading was unrelated to baseline Cr levels (r=0.33, not significant). Supplementation did not significantly improve exercise performance (Cr group: 39.1 ± 0.9 vs. 39.8 ± 0.8 km and placebo group: 39.3 ± 0.8 vs. 39.2 ± 1.1 km) or change plasma lactate concentrations. Plasma concentrations of ammonia (NH₃) (P < 0.05) and hypoxanthine (Hx) (P < 0.01) were lower in the Cr group from T1 to T2. Our results indicate that Cr supplementation alters the metabolic response during sustained high‐intensity submaximal exercise. Plasma data suggest that nett intramuscular adenine nucleotide degradation may be decreased in the presence of enhanced intramuscular TCr concentration even during submaximal exercise.     

The effect of HMB supplementation on body composition, fitness, hormonal and inflammatory mediators in elite adolescent volleyball players: a prospective randomized, double-blind, placebo-controlled study

The use of ergogenic nutritional supplements is becoming inseparable from competitive sports. β-Hydroxy-β-Methylbutyric acid (HMB) has recently been suggested to promote fat-free mass (FFM) and strength gains during resistance training in adults. In this prospective randomized, double-blind, placebo-controlled study, we studied the effect of HMB (3 g/day) supplementation on body composition, muscle strength, anaerobic and aerobic capacity, anabolic/catabolic hormones and inflammatory mediators in elite, national team level adolescent volleyball players (13.5–18 years, 14 males, 14 females, Tanner stage 4–5) during the first 7 weeks of the training season. HMB led to a significant greater increase in FFM by skinfold thickness (56.4 ± 10.2 to 56.3 ± 8.6 vs. 59.3 ±  11.3 to 61.6 ± 11.3 kg in the control and HMB group, respectively, p < 0.001). HMB led to a significant greater increase in both dominant and non-dominant knee flexion isokinetic force/FFM, measured at fast (180°/sec) and slow (60°/sec) angle speeds, but had no significant effect on knee extension and elbow flexion and extension. HMB led to a significant greater increase in peak and mean anaerobic power determined by the Wingate anaerobic test (peak power: 15.5 ± 1.6 to 16.2 ± 1.2 vs. 15.4 ± 1.6 to 17.2 ± 1.2 watts/FFM, mean power: 10.6 ± 0.9 to 10.8 ± 1.1 vs. 10.7 ± 0.8 to 11.8 ± 1.0 watts/FFM in control and HMB group, respectively, p < 0.01), with no effect on fatigue index. HMB had no significant effect on aerobic fitness or on anabolic (growth hormone, IGF-I, testosterone), catabolic (cortisol) and inflammatory mediators (IL-6 and IL-1 receptor antagonist). HMB supplementation was associated with greater increases in muscle mass, muscle strength and anaerobic properties with no effect on aerobic capacity suggesting some advantage for its use in elite adolescent volleyball players during the initial phases of the training season. These effects were not accompanied by hormonal and inflammatory mediator changes.