J. M. C. Soares

Exercise, Muscle Damage and Fatigue

SummaryFatigue as a functional sign and muscle damage as a structural sign can be observed after prolonged exercise like marathon running or after strenuous exercise, especially with the involvement of eccentric contractions. For fatigue due to prolonged exercise, hypoxic conditions and the formation of free oxygen radicals seem to be of aetiological importance, resulting in an elevated lysosomal activity. Eccentric exercise of high intensity rather results in a mechanical stress to the fibres. Although these different mechanisms can be discerned experimentally, both result in similar impairments of muscle function. A good training status may attenuate the clinical signs of fatigue and muscle damage. The symptoms and events occurring during delayed onset of muscle soreness (DOMS) can be explained by a cascade of events following structural damage to muscle proteins.

Effects of resistance and multicomponent exercise on lipid profiles of older women

OBJECTIVE The purpose of this study was to compare the effects of two exercise programs of 8 months duration on lipid profiles in older women. METHODS In 2006, 77 women from Porto, Portugal, aged 60-79 years were randomly assigned into a multicomponent exercise (ME) program or resistance exercise (RE) program. Before- and after-training, body composition, daily physical activity (DPA), aerobic endurance, plasma concentrations of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) were assessed. Training was performed twice weekly. The protocol for the ME included aerobic exercise, muscular endurance exercises and activities targeted to improve balance and flexibility. The RE protocol included leg press, leg extensions and curls, double chest raises, lateral raises, overhead press and abdominal exercises. RESULTS Significant decreases in TG (-5.1%, p=0.006), and significant increases in HDL-C (9.3%, p<0.001) were observed in the ME group. Following 8 months no significant changes were observed on lipid profile in RE group, although lipid- and lipoprotein-related variables tended to alter favorably. Both regimens resulted in significant improvements on 6-min walk test (6.4%, p=0.001 for ME; and 6.0%, p=0.044 for RE). No significant changes were observed in total DPA and body fat in either group after exercise interventions. No significant correlations were found between body composition, physical activity, aerobic endurance, and lipid profile. CONCLUSIONS The data suggested that 8 months of ME may be more effective than RE for inducing favorable changes in plasma lipoprotein and lipid profiles.

Skeletal muscle damage during tourniquet-induced ischaemia

SummaryMuscle biopsies from the vastus lateralis muscle of patients who had undergone anterior cruciate ligament surgery under conditions of tourniquet-induced ischaemia were examined under the electron microscope at different periods of time up to 90 min of ischaemia. The severity of the alterations in ultrastructure appeared to depend on the period of ischaemia. The pathological changes consisted of accumulation of lysosomes, persistent intrafibre oedema, and some extracellular oedema. Signs of fibre necrosis were found after 90 min of ischaemia. Capillary ultrastructure was only altered with regard to some swelling of the endothelium and marked thickening of the basement membrane. It was concluded that skeletal muscle could be severely affected even during relatively short periods of ischaemia, which might facilitate the development of muscle atrophy during immobilization after orthopaedic surgery.

Effects of training and an anabolic steroid on murine red skeletal muscle. A stereological analysis.

The purpose of this study was the evaluation of changes induced by training (swimming 1 h/day, 5 days/week, 6 weeks) and an anabolic hormone (nandrolone decanoate, intramuscular injections of 15 mg.kg-1 per week) on fiber size, capillarization and mitochondrial fraction of murine soleus muscle. The animals (n = 32) were divided into 4 groups: a control group (C), that received the arachis oil carrier; a steroid group (S), that received the hormone; a training group (T), and a group that was submitted to training and to the administration of hormone (S + T). The soleus muscle was selected for quantitative light- and electron-microscopic evaluation. The muscle fiber size was increased in group T and decreased in groups S and S + T. The axial length of capillaries per unit volume of muscle decreased significantly in groups S and T. The number of capillaries per number of fibers showed a significant decrease in groups S and S + T and an increase in group T. The mitochondrial content decreased in group S, which suggested that anabolic steroids can be harmful for these organelles. This hypothesis was confirmed by histological evaluation at the electron-microscopic level. Many swollen and disrupted mitochondria were found in groups S and S + T. The results suggest that administration of nandrolone decanoate may have some deleterious effects on the muscle respiratory system (capillaries and mitochondria).

Administration of tourniquet

One hindlimb of mice was subjected to 60, 90 and 120 min ischemia by application of a tourniquet followed by a 60-min reperfusion period. An additional experimental group received a tourniquet for 90 min without subsequent reperfusion. The soleus muscle (from the contralateral side also as control) was removed and evaluated for muscle weight, protein weight, protein content, and glutathione concentrations. Ischemia alone without subsequent reperfusion did not produce significant changes. With postischemic reperfusion, the protein content and muscle weight increased, probably because of an increased capillary permeability, leading to muscle edema. Oxidative stress was also present during reperfusion, correlating well with the changes in protein content. The intensity of these alterations appeared to depend on the period of ischemia.

Analysis of fatigue development during elite male handball matches.

Abstract Póvoas, SCA, Ascensão, AAMR, Magalhães, J, Seabra, AFT, Krustrup, P, Soares, JMC, and Rebelo, ANC. Analysis of fatigue development during elite male handball matches. J Strength Cond Res 28(9): 2640–2648, 2014—This study aimed at describing the physiological demands and fatigue development during elite male handball matches. Our hypothesis was that players perform multiple high-intensity activities during periods of the game and develop temporary and end-match neuromuscular fatigue. Time-motion analyses and heart rate (HR) recordings were performed in 40 players during 12 competitive matches. Blood samples were collected, and sprint, jump, and intermittent exercise performance (Yo-Yo Intermittent Endurance level 2 test [YYIE2]) was assessed for 18 players at baseline conditions and after 2 competitive matches, and additional blood sampling and testing were performed for 12 of these players during a friendly match. The time spent with high-intensity running (4.4 ± 2.0 to 3.1 ± 1.7%), the frequency of demanding actions (61 ± 5 to 54 ± 6), and the time with HR above 80% HRmax (62 ± 21 to 41 ± 17%) were lowered from the first to the second half. Average blood lactate during the match was 3.6 ± 2.1 (1.3–8.6) mM. Plasma free fatty acids (FFA), glycerol, glucose, and uric acid increased (p ⩽ 0.05) during the first half and plasma FFA and glycerol increased further (p ⩽ 0.05) during the second half. After an intense period in the second half, sprint performance was decreased by 3.9 ± 4.9%. After the match, YYIE2 (33.4 ± 8.7%), vertical jump (7.4 ± 6.5%), and 20-m sprint performance (1.6 ± 2.6%) was lower (p ⩽ 0.05) than at baseline. This study showed that the intensity is high in certain periods during elite male handball games and that physical performance is impaired both temporarily during and toward the end of games confirming our hypothesis. These findings enables physical trainers and coaches to plan and design proper game-specific training exercises aiming at delaying both temporary and end-game fatigue and strengthen the physiological rationale for the need for substitutions in various stages of match-play.

Physiological demands of elite team handball with special reference to playing position

Abstract Póvoas, SCA, Ascensão, AAMR, Magalhães, J, Seabra, AF, Krustrup, P, Soares, JMC, and Rebelo, ANC. Physiological demands of elite team handball with special reference to playing position. J Strength Cond Res 28(2): 430–442, 2014—This study aimed to analyze the physiological demands of match play for different playing positions in elite male team handball. Time motion (N = 30) and heart rate (HR; N = 70) data were recorded throughout 10 official matches. The mean distance covered by backcourt players (4.96 ± 0.64 km) was greater (p ⩽ 0.02) than for wings and pivots (4.23 ± 0.52 and 3.91 ± 0.51 km, respectively). Backcourt players spent less time standing still and walking (∼76%) than wings and pivots (∼80%) (p ⩽ 0.03), and wings spent more time sprinting than the other playing positions. Backcourt players (122.9 ± 17.0) and pivots (126.8 ± 33.0) performed more high-demanding actions per game than wings (54.6 ± 15.6) (p = 0.01). The time spent by pivots in high-intensity activities decreased from the first to the second half (4.1 ± 2.4 to 2.7 ± 0.9%; p ⩽ 0.01), while backcourt players showed a decrease in high-demanding playing actions (p ⩽ 0.05). Backcourt players and pivots had higher mean (84 ± 9 and 83 ± 9% vs. 79 ± 10%; p ⩽ 0.03) and peak effective HR, and percentage of total time at intensities >80% maximal HR (HRmax) than wings. The fraction of total time spent at intensities >80% HRmax decreased for all outfield playing positions in the second half (from 39–76 to 30–46%). Competitive team handball involves position-specific differences in the physiological demands. Furthermore, exercise intensity decreases from the first to the second half for all outfield playing positions suggesting that these players experience neuromuscular fatigue. Training of elite handball players should comprise high-intensity position-specific exercises aiming at improving the ability to maintain a high exercise intensity throughout the game.

Isokinetic strength benefits after 24 weeks of multicomponent exercise training and combined exercise training in older adults.

Background and aims: Studies that have attempted to address the influence of exercise programs on muscle strength have usually analyzed single exercise training types. They have not often addressed multicomponent exercise interventions that combine strength, flexibility, balance and aerobic training. The aim of the present study was to assess and compare improvements in muscle strength induced by 24 weeks of two training regimens in elderly adults aged 65–82 years. Methods: Participants underwent a multicomponent exercise program (ME, n=25, 69.4±4.1 yrs) or combined ME plus resistance training (CE, n=24, 68.7±4.2 yrs). Maximum strength of knee extensors (KE) and flexors (KF) was measured at 60°/s and 180°/s with an isokinetic dynamometer before and 12 and 24 weeks after the training programs. Results: The CE group showed a significant increase in maximum voluntary knee extensors (22.3%, p<0.001) and knee flexors (29.6%, p<0.001) at 180°/s in the non-dominant leg, in knee extensor torque at 60°/s in the dominant (6.7%, p=0.023) and non-dominant leg (17.3%, p<0.001) and in knee flexor torque at 60°/s in dominant (16.4%, p=0.020) and non-dominant leg (24.2%, p<0.001). No significant changes were observed in the ME group after 24 weeks of training. Conclusions: The present study indicates that twice-weekly ME has a limited effect on isokinetic muscle strength. Our results also emphasize that adding moderate intensity resistance exercise twice a week to a ME protocol is sufficient to induce higher and significant strength improvements in healthy older subjects.

Reliability and validity of Yo-Yo tests in 9- to 16-year-old football players and matched non-sports active schoolboys

Abstract The purpose of this study was to examine the test–retest reliability and construct validity of three age-adapted Yo-Yo intermittent tests in football players aged 9–16 years (n = 70) and in age-matched non-sports active boys (n = 72). Within 7 days, each participant performed two repetitions of an age-related intensity-adapted Yo-Yo intermittent test, i.e. the Yo-Yo intermittent recovery level 1 childrens test for 9- to 11-year-olds; the Yo-Yo intermittent endurance level 1 for 12- to 13-year-olds and the Yo-Yo intermittent endurance level 2 test for 14- to 16-year-olds. Peak heart rate (HRpeak) was determined for all tests. The distance covered in the tests was 57% (1098 ± 680 vs. 700 ± 272 m), 119% (2325 ± 778 vs. 1062 ± 285 m) and 238% (1743 ± 460 vs. 515 ± 113 m) higher (p ≤ .016), respectively for football-trained than for non-sports active boys aged 9–11, 12–13 and 14–16 years. The typical errors of measurement for Yo-Yo distance, expressed as a percentage of the coefficient of variation (confidence interval), were 11.1% (9.0–14.7%), 10.1% (8.1–13.7%) and 8.5% (6.7–11.7%) for football players aged 9–11, 12–13 and 14–16 years, respectively, with corresponding values of 9.3% (7.4–12.8%), 10.2% (8.1–14.0%) and 8.5% (6.8–11.3%) for non-sports active boys. Intraclass correlation coefficient values for test–retest were excellent in both groups (range: 0.844–0.981). Relative HRpeak did not differ significantly between the groups in test and retest. In conclusion, Yo-Yo intermittent test performances and HRpeak are reliable for 9- to 16-year-old footballers and non-sports active boys. Additionally, performances of the three Yo-Yo tests were seemingly better for football-trained than for non-sports active boys, providing evidence of construct validity.

Are former elite athletes more protected against metabolic syndrome

BACKGROUND AND PURPOSE Scientific literature offers no epidemiological data regarding prevalence and protective factors for the metabolic syndrome (MetSyn) among former athletes. The aim of this cross-sectional study was to investigate whether former athletes are better protected against MetSyn and if this hypothetical protection is dependent on sex, career, or later lifestyle. METHODS We assessed demographic, behavioral, physical, and biochemical characteristics in a population of 491 subjects of both sexes. RESULTS After adjustment for potential confounding factors, we found no significant differences in the likelihood of MetSyn among former elite, non-elite, and non-athletes. Likewise, sex and previous sport intensity did not reveal a significant association with the syndrome. However, both former elite [odds ratio (OR) 0.20, p=0.020] and non-elite athletes (OR 0.50, p=0.044) who after career termination engaged in the recommended amounts of physical activity, showed a reduced likelihood for the MetSyn. CONCLUSIONS Former athletes tend to adopt healthier lifestyles, which may give them an advantage regarding the risk factors that delineate the syndrome. Furthermore, physical activity engagement at recommended levels seems to play an important role in the association with MetSyn, even in subjects who have never been athletes.