Leukocyte subset responses during exercise under heat stress with carbohydrate or water intake

Purpose: This study investigated leukocyte subset responses to moderate-intensity exercise under heat stress, with water (W) or carbohydrate (CHO) drink ingestion. Methods: In repeated trials, 13 soldiers consumed either a W or CHO drink during 3 h of walking at 4.4 km center dot h(-1) with a 5% gradient (15 min rest per hour) under heat stress (35 C and 55% relative humidity). The soldiers wore combat uniforms and carried water bottles and dummy rifles and ammunition, altogether weighing about 11.5 +/- 1.0 kg. Results: Plasma glucose concentration was significantly higher with CHO than W ingestion during exercise (p < 0.01). There were no significant differences between W and CHO conditions in exercise performance, plasma cortisol concentration, heart rate, or core temperature. CHO ingestion significantly moderated the increases in leukocyte (83% in W, 28% in CHO; p < 0.001), monocyte (60% in W, 34% in CHO; p < 0.05), and granulocyte counts (120% in W, 30% in CHO; p < 0.001), but not in lymphocyte count (41% in W, 25% in CHO). Conclusions: The increases in leukocyte and subset counts during moderate-intensity exercise under heat stress may be comparable to those observed during intense exercise in cool conditions. The response of immune cell counts is blunted by CHO intake during moderate-intensity exercise in the heat, and may not occur through the cortisol pathway.

Differential regulation of PGC-1 alpha expression in rat liver and skeletal muscle in response to voluntary running

Background: The beneficial actions of exercise training on lipid, glucose and energy metabolism and insulin sensitivity appear to be in part mediated by PGC-1 alpha. Previous studies have shown that spontaneously exercised rats show at rest enhanced responsiveness to exogenous insulin, lower plasma insulin levels and increased skeletal muscle insulin sensitivity. This study was initiated to examine the functional interaction between exercise-induced modulation of skeletal muscle and liver PGC-1 alpha protein expression, whole body insulin sensitivity, and circulating FFA levels as a measure of whole body fatty acid (lipid) metabolism. Methods: Two groups of male Wistar rats (2 Mo of age, 188.82 +/- 2.77 g BW) were used in this study. One group consisted of control rats placed in standard laboratory cages. Exercising rats were housed individually in cages equipped with running wheels and allowed to run at their own pace for 5 weeks. At the end of exercise training, insulin sensitivity was evaluated by comparing steady-state plasma glucose (SSPG) concentrations at constant plasma insulin levels attained during the continuous infusion of glucose and insulin to each experimental group. Subsequently, soleus and plantaris muscle and liver samples were collected and quantified for PGC-1 alpha protein expression by Western blotting. Collected blood samples were analyzed for glucose, insulin and FFA concentrations. Results: Rats housed in the exercise wheel cages demonstrated almost linear increases in running activity with advancing time reaching to maximum value around 4 weeks. On an average, the rats ran a mean (Mean +/- SE) of 4.102 +/- 0.747 km/day and consumed significantly more food as compared to sedentary controls (P < 0.001) in order to meet their increased caloric requirement. Mean plasma insulin (P < 0.001) and FFA (P < 0.006) concentrations were lower in the exercise-trained rats as compared to sedentary controls. Mean steady state plasma insulin (SSPI) and glucose (SSPG) concentrations were not significantly different in sedentary control rats as compared to exercise-trained animals. Plantaris PGC-1 alpha protein expression increased significantly from a 1.11 +/- 0.12 in the sedentary rats to 1.74 +/- 0.09 in exercising rats (P < 0.001). However, exercise had no effect on PGC-1 alpha protein content in either soleus muscle or liver tissue. These results indicate that exercise training selectively up regulates the PGC-1 alpha protein expression in high-oxidative fast skeletal muscle type such as plantaris muscle. Conclusion: These data suggest that PGC-1 alpha most likely plays a restricted role in exercise-mediated improvements in insulin resistance (sensitivity) and lowering of circulating FFA levels.

Is acute static stretching able to reduce the time to exhaustion at power output corresponding to maximal oxygen uptake?

Samogin Lopes, FA, Menegon, EM, Franchini, E, Tricoli, V, and de M. Bertuzzi, RC. Is acute static stretching able to reduce the time to exhaustion at power output corresponding to maximal oxygen uptake? J Strength Cond Res 24(6): 1650-1656, 2010-This study analyzed the effect of an acute static stretching bout on the time to exhaustion (T(lim)) at power output corresponding to (V) over dotO(2)max. Eleven physically active male subjects (age 22.3 +/- 2.8 years, (V) over dotO(2)max 2.7 +/- 0.5 L . min(-1)) completed an incremental cycle ergometer test, 2 muscle strength tests, and 2 maximal tests to exhaustion at power output corresponding to (V) over dotO(2)max with and without a previous static stretching bout. The T(lim) was not significantly affected by the static stretching (164 +/- 28 vs. 150 +/- 26 seconds with and without stretching, respectively, p = 0.09), but the time to reach (V) over dotO(2)max (118 +/- 22 vs. 102 +/- 25 seconds), blood-lactate accumulation immediately after exercise (10.7 +/- 2.9 vs. 8.0 +/- 1.7 mmol . L(-1)), and oxygen deficit (2.4 +/- 0.9 vs. 2.1 +/- 0.7 L) were significantly reduced (p <= 0.02). Thus, an acute static stretching bout did not reduce T(lim) at power output corresponding to (V) over dotO(2)max possibly by accelerating aerobic metabolism activation at the beginning of exercise. These results suggest that coaches and practitioners involved with aerobic dependent activities may use static stretching as part of their warm-up routines without fear of diminishing high-intensity aerobic exercise performance.

Taekwondo: physiological responses and match analysis

Matsushigue, KA, Hartmann, K, and Franchini, E. Taekwondo: Physiological responses and match analysis. J Strength Cond Res 23(4): 1112-1117, 2009-The aim of the present study was to determine the time structure and physiological responses during Songahm Taekwondo (TKD) competition and to compare these variables between winner and non-winner athletes. Fourteen men subjects were analyzed. Blood lactate concentration (LA) and heart rate (HR) were determined before and after the match. The match was filmed for the determination of the number of techniques used, the duration of effort and rest periods (RPs), and the interval between high-intensity movements (HM). Post-match LA was 7.5 +/- 3.8 mmol.L(-1), HR was 183 +/- 9 b.min(-1), and HM was 31 +/- 16 seconds. The mean effort time (862 seconds) did not differ from mean interval time (8 +/- 3 seconds). Winners used a smaller total number of techniques, but post-match LA or HR did not differ from that of non-winners. In conclusion, the glycolytic metabolism was not the predominant energy source and the physiological responses did not differ between winners and non-winners. Coaches and sports scientists should prepare a technical or physical training session considering the low glycolytic contribution in this sport, hence the training protocol should involve high-intensity movements interspersed with longer RPs to provide the creatine phosphate recovery, with special attention given to the technical quality of TKD skills and not to higher technique volume during a simulation of matches.

The effect of carbohydrate mouth rinse on maximal strength and strength endurance

It has been previously reported that carbohydrate (CHO) mouth rinse can improve exercise performance. The proposed mechanism involves increased activation of brain regions believed to be responsible for reward/motivation and motor control. Since strength-related performance is affected by central drive to the muscles, it seems reasonable to hypothesize that the positive CNS response to oral CHO sensing may counteract the inhibitory input from the muscle afferent pathways minimizing the drop in the central drive. The purpose of the current study was to test if CHO mouth rinse affects maximum strength and strength endurance performance. Twelve recreationally strength-trained healthy males (age 24.08 +/- 2.99 years; height 178.09 +/- 6.70 cm; weight 78.67 +/- 8.17 kg) took part in the study. All of the tests were performed in the morning, after an 8 h overnight fasting. Subjects were submitted to a maximum strength test (1-RM) and a strength endurance test (six sets until failure at 70% of 1-RM), in separate days under three different experimental conditions (CHO mouth rinse, placebo-PLA mouth rinse and control-CON) in a randomized crossover design. The CHO mouth rinse (25 ml) occurred before every attempt in the 1-RM test, and before every set in the endurance strength test. Blood glucose and lactate were measured immediately before and 5 min post-tests. There were no significant differences in 1-RM between experimental conditions (CHO 101 +/- 7.2 kg; PLA 101 +/- 7.4 kg; CON 101 +/- 7.2 kg; p = 0.98). Furthermore, there were no significance between trial differences in the number of repetitions performed in each set (p = 0.99) or the total exercise volume (number of repetitions x load lifted [kg]) (p = 0.98). A main effect for time (p < 0.0001) in blood lactate concentration was observed in both tests (1-RM and strength endurance). Blood glucose concentration did not differ between conditions. In conclusion, CHO mouth rinse does not affect maximum strength or strength endurance performance.

Influence of strength training background on postactivation potentiation response

Batista, MAB, Roschel, H, Barroso, R, Ugrinowitsch, C, and Tricoli, V. Influence of strength training background on postactivation potentiation response. J Strength Cond Res 25(9): 2496-2502, 2011-The aim of this study was to evaluate the influence of the subjects` level of maximal dynamic strength and training background on postactivation potentiation (PAP). A group of 23 subjects, composed of power track-and-field athletes (PT = 8), bodybuilders (BB = 7), and physically active subjects (PA = 8), participated in the study. Maximal dynamic strength (1 repetition maximum test) was assessed in the leg press exercise for subjects` characterization. Their countermovement vertical jump (CMJ) performance was assessed before and after 2 different conditioning activity (CA) protocols (1 or 3 maximum voluntary isometric contractions [MVICs] of 5-second duration in the leg press exercise) or after control (no CA), performed on separate days. No significant differences among groups were found for CMJ height or take-off velocity after any of the CA protocols (p <= 0.05). However, individual analysis showed that some subjects increased performance in response to the CA, despite their previous training history. We concluded that subjects` level of maximal dynamic strength and training background have no influence on PAP manifestation. Our data suggest that coaches should individually identify the athletes that are PAP responders before introducing MVICs as part of their warm-up routines.

Efficacy and safety of concurrent training in systemic sclerosis

Pinto, ALS, Oliveira, NC, Gualano, B, Christmann, RB, Painelli, VS, Artioli, GG, Prado, DML, and Lima, FR. Efficacy and safety of concurrent training in systemic sclerosis. J Strength Cond Res 25(5): 1423-1428, 2011-The optimal training model for patients with systemic sclerosis (SSc) is unknown. In this study, we aimed to investigate the effects of a 12-week combined resistance and aerobic training program (concurrent training) in SSc patients. Eleven patients with no evidence of pulmonary involvement were recruited for the exercise program. Lower and upper limb dynamic strengths (assessed by 1 repetition maximum [1RM] of a leg press and bench press, respectively), isometric strength (assessed by back pull and handgrip tests), balance and mobility (assessed by the timed up-and-go test), muscle function (assessed by the timed-stands test), Rodnan score, digital ulcers, Rayland`s phenomenon, and blood markers of muscle inflammation (creatine kinase and aldolase) were assessed at baseline and after the 12-week program. Exercise training significantly enhanced the 1RM leg press (41%) and 1RM bench press (13%) values and back pull (24%) and handgrip strength (11%). Muscle function was also improved (15%), but balance and mobility were not significantly changed. The time-to-exhaustion was increased (46.5%, p = 0.0004), the heart rate at rest condition was significantly reduced, and the workload and time of exercise at ventilatory thresholds and peak of exercise were increased. However, maximal and submaximal (V)over dotO(2) were unaltered (p > 0.05). The Rodnan score was unchanged, and muscle enzymes remained within normal levels. No change was observed in digital ulcers and Raynaud`s phenomenon. This is the first study to demonstrate that a 12-week concurrent training program is safe and substantially improves muscle strength, function, and aerobic capacity in SSc patients.

Abnormalities in arterial-ventricular coupling in older healthy persons are attenuated by sodium nitroprusside

Chantler PD, Nussbacher A, Gerstenblith G, Schulman SP, Becker LC, Ferrucci L, Fleg JL, Lakatta EG, Najjar SS. Abnormalities in arterial-ventricular coupling in older healthy persons are attenuated by sodium nitroprusside. Am J Physiol Heart Circ Physiol 300: H1914-H1922, 2011. First published March 4, 2011; doi:10.1152/ajpheart.01048.2010.-The coupling between arterial elastance (E(A); net afterload) and lea ventricular elastance (E(LV); pump performance), known as E(A)/E(LV), is a key determinant of cardiovascular performance and shifts during exercise due to a greater increase in E(LV) versus E(A). This normal exercise-induced reduction in E(A)/E(LV) decreases with advancing age. We hypothesized that sodium. nitroprusside (SNP) can acutely ameliorate the age-associated deficits in E(A)/E(LV). At rest and during graded exercise to exhaustion, EA was characterized as end-systolic pressure/stroke volume and E(LV) as end-systolic pressure/end-systolic volume. Resting E(A)/E(LV): did not differ between old (70 +/- 8 yr. n = 15) and young (30 +/- 5 yr. n = 17) subjects because of a tandem increase in E(A) and E(LV) in older subjects. During peak exercise, a blunted increase in E(LV) in old (7.8 +/- 3.1 mmHg/ml) versus young (11.4 +/- 6.5 mmHg/ml) subjects blunted the normal exercise-induced decline in E(A)/E(LV) in old (0.25 +/- 0.11) versus young (0.16 +/- 0.05) subjects. SNP administration to older subjects lowered resting E(A)/E(LV) by 31% via a reduction E(A) (10%) and an increase in E(LV) (47%) and lowered peak exercise E(A)/E(LV) (36%) via an increase in E(LV) (68%) without a change in E(A). Importantly, SNP attenuated the age-associated deficits in E(A)/E(LV) and E(LV) during exercise, and at peak exercise E(A)/E(LV) in older subjects on drug administration did not differ from young subjects without drug administration. In conclusion, some age-associated deficiencies in E(A)/E(LV), E(A), and E(LV), in older subjects can be acutely abolished by SNP infusion. This is relevant to common conditions in older subjects associated with a significant impairment of exercise performance such as frailty or heart failure with preserved ejection fraction.

Effect of low-dose combined oral contraceptive on aerobic capacity and anaerobic threshold level in active and sedentary young women

Background: The purpose of this study was to evaluate the effect of long-term use of oral contraceptives (DC) containing 0.20 mg of ethinylestradiol (EE) combined with 0.15 mg of gestodene (GEST) on the peak aerobic capacity and at the anaerobic threshold (AT) level in active and sedentary young women. Study Design: Eighty-eight women (23 +/- 2.1 years old) were divided into four groups active-OC (G1), active-NOC (G2), sedentary-OC (G3) and sedentary-NOC (G4) and were submitted to a continuous ergospirometric incremental test on a cycloergometer with 20 to 25 W min(-1) increments. Data were analyzed by two-way ANOVA with Tukey post hoc test. Level of significance was set at 5%. Results: The OC use effect for the variables relative and absolute oxygen uptake VO(2) mL kg(-1) min(-1); VO(2), L min(-1), respectively), carbon dioxide output (VCO(2), L min(-1)), ventilation (VE, L min(-1)), heart rate (HR, bpm), respiratory exchange ratio (RER) and power output (W) data, as well as the interaction between OC use and exercise effect on the peak of test and at the AT level did not differ significantly between the active groups (G1 and G2) and the sedentary groups (G3 and G4). As to the exercise effect, for all variables studied, it was noted that the active groups presented higher values for the variables VO(2), VCO(2), VE and power output (p<.05) than the sedentary groups. The RER and HR were similar (p>.05) at the peak and at the AT level between G1 vs. G3 and G2 vs. G4. Conclusions: Long-term use of OC containing EE 0.20 mg plus GEST 0.15 mg does not affect aerobic capacity at the peak and at the AT level of exercise tests. (C) 2010 Elsevier Inc. All rights reserved.

Physiological responses to the menstrual cycle - Implications for the development of heat illness in female athletes

Fluctuations in estrogen and progesterone during the menstrual cycle can cause changes in body systems other than the reproductive system. For example, progesterone is involved in the regulation of fluid balance in the renal tubules and innervation of the diaphragm via the phrenic nerve. However, few significant changes in the responses of the cardiovascular and respiratory systems, blood lactate, bodyweight, performance and ratings of perceived exertion are evident across the cycle. Nevertheless, substantial evidence exists to suggest that increased progesterone levels during the luteal phase cause increases in both core and skin temperatures and alter the temperature at which sweating begins during exposure to both ambient and hot environments. As heat illness is characterised by a significant increase in body temperature, it is feasible that an additional increase in core temperature during the luteal phase could place females at an increased risk of developing heat illness during this time. In addition, it is often argued that physiological gender differences such as oxygen consumption, percentage body fat and surface area-to-mass ratio place females at a higher risk of heat illness than males. This review examines various physiological responses to heat exposure during the menstrual cycle at rest and during exercise, and considers whether such changes increase the risk of heat illness in female athletes during a particular phase of the menstrual cycle.

Optimising high-intensity treadmill training using the running speed at maximal O-2 uptake and the time for which this can be maintained

The aim of this study was to compare the effects of two high-intensity, treadmill interval-training programs on 3000-m and 5000-m running performance. Maximal oxygen uptake ((V) over dot O-2max), the running speed associated with (V) over dot O-2max (nu (V) over dot O-2max), the time for which nu (V) over dot O-2max can be maintained (T-max), running economy (RE), ventilatory threshold (VT) and 3000-m and 5000-m running times were determined in 27 well-trained runners. Subjects were then randomly assigned to three groups; (1) 60% T-max (2) 70% T-max and (3) control. Subjects in the control group continued their normal training and subjects in the two T-max groups undertook a 4-week treadmill interval-training program with the intensity set at nu (V) over dot O-2max and the interval duration at the assigned T-max. These subjects completed two interval-training sessions per week (60% T-max = six intervals/session, 70% T-max group = five intervals/session). Subjects were re-tested on all parameters at the completion of the training program. There was a significant improvement between pre- and post-training values in 3000-m time trial (TT) performance in the 60% T-max group compared to the 70% T,,a, and control groups [mean (SE); 60% T-max = 17.6 (3.5) s, 70% T-max = 6.3 (4.2) s, control = 0.5 (7.7) s]. There was no significant effect of the training program on 5000-m TT performance [60% T-max = 25.8 (13.8) s, 70% T-max = 3.7 (11.6) s, control = 9.9 (13.1) s]. Although there were no significant improvements in (V) over dot O-2max, nu (V) over dot (2max) and RE between groups, changes in (V) over dot O-2max and RE were significantly correlated with the improvement in the 3000-m TT. Furthermore, VT and T-max were significantly higher in the 60% Tmax group post-compared to pre-training. In conclusion, 3000-m running performance can be significantly improved in a group of well-trained runners, using a 4-week treadmill interval training program at nu (V) over dot O-2max with interval durations of 60% T-max.

A comparison of two methods for the calculation of accumulated oxygen deficit

The aim of this study was to compare accumulated oxygen deficit data derived using two different exercise protocols with the aim of producing a less time-consuming test specifically for use with athletes. Six road and four track male endurance cyclists performed two series of cycle ergometer tests. The first series involved five 10 min sub-maximal cycle exercise bouts, a (V) over dotO(2peak) test and a 115% (V) over dotO(2peak) test. Data from these tests were used to estimate the accumulated oxygen deficit according to the calculations of Medbo et al. (1988). In the second series of tests, participants performed a 15 min incremental cycle ergometer test followed, 2 min later, by a 2 min variable resistance test in which they completed as much work as possible while pedalling at a constant rate. Analysis revealed that the accumulated oxygen deficit calculated from the first series of tests was higher (P< 0.02) than that calculated from the second series: 52.3 +/- 11.7 and 43.9 +/- 6.4 ml . kg(-1), respectively (mean +/- s). Other significant differences between the two protocols were observed for (V) over dot O-2peak, total work and maximal heart rate; all were higher during the modified protocol (P

Ventilação não invasiva durante o exercício em pacientes com DPOC: revisão sistemática com meta-análise

Mestrado em Fisioterapia

Monitoring of biological markers indicative of doping: the athlete biological passport

The athlete biological passport (ABP) was recently implemented in anti-doping work and is based on the individual and longitudinal monitoring of haematological or urine markers. These may be influenced by illicit procedures performed by some athletes with the intent to improve exercise performance. Hence the ABP is a valuable tool in the fight against doping. Actually, the passport has been defined as an individual and longitudinal observation of markers. These markers need to belong to the biological cascade influenced by the application of forbidden hormones or more generally, affected by biological manipulations which can improve the performance of the athlete. So far, the haematological and steroid profile modules of the ABP have been implemented in major sport organisations, and a further module is under development. The individual and longitudinal monitoring of some blood and urine markers are of interest, because the intraindividual variability is lower than the corresponding interindividual variability. Among the key prerequisites for the implementation of the ABP is its prospect to resist to the legal and scientific challenges. The ABP should be implemented in the most transparent way and with the necessary independence between planning, interpretation and result management of the passport. To ensure this, the Athlete Passport Management Unit (APMU) was developed and the WADA implemented different technical documents associated to the passport. This was carried out to ensure the correct implementation of a profile which can also stand the challenge of any scientific or legal criticism. This goal can be reached only by following strictly important steps in the chain of production of the results and in the management of the interpretation of the passport. Various technical documents have been then associated to the guidelines which correspond to the requirements for passport operation. The ABP has been completed very recently by the steroid profile module. As for the haematological module, individual and longitudinal monitoring have been applied and the interpretation cascade is also managed by a specific APMU in a similar way as applied in the haematological module. Thus, after exclusion of any possible pathology, specific variation from the individual norms will be then considered as a potential misuse of hormones or other modulators to enhance performance.