International SportMed Journal - Volume 12, Issue 2, 2011
Volume 12, Issue 2, 2011
Blood pressure responses and heart rate variability after resistance exercise with different intensities and same workload : original research articleSource: International SportMed Journal 12, pp 53 –67 (2011)More Less
Background: There is little information about heart rate variability (HRV) in the context of studies involving post-exercise hypotension, principally resistance exercise.
Research question: This study aimed to verify the responses of blood pressure (BP) after resistance exercise performed at three different intensities with the same volume.
Type of study: The type of study design used to answer the question was transversal.
Methods: Ten non-hypertensive men randomly performed three sessions of resistance exercises at different intensities (40, 60 and 80% 1RM) with the same volume. BP and heart rate variability (HRV) were monitored for 60min after interventions.
Results: The results were expressed as mean and standard deviation. The diastolic BP remained low in the average monitoring period in the intensities of 40% (rest=68.2±7.5; post=56.5±6.5 mmHg; p=0.0001), 60% (rest=68.0±5.0; post=56.6±6.3 mmHg; p=0.0001) and 80% 1RM (rest=69.6±8.0; post=58.8±7.4 mmHg; p=0.0001). The same was true for the mean BP at the intensities of 40% (rest=86.5±5.8; post=76.1±6.3 mmHg; p=0.0001), 60% (rest=86.3±5.6; post=76.8±7.1 mmHg; p=0.0001) and 80% 1RM (rest=87.6±5.4; post=78.6±7.01 mmHg; p=0.0001). Although the average systolic BP of the post-exercise monitoring period was very similar across exercise intensities, these values were statistically lower than those at rest only at 40% 1RM (rest=123.2±8.9; post=115.3±10.0 mmHg; p=0.04). HRV showed greater sympathetic activation after the exercise session regardless of intensity.
Conclusion: There aren't differences in the responses of BP after exercise at different intensities and same workload. Thus resistance exercise at any of these three intensities can promote BP reductions in non-hypertensive individuals. The execution of resistance exercise at light intensities may be interesting for exercise prescription in non-hypertensive subjects, because there are sufficient strength gains related to health, besides providing greater adherence to exercise practice.
A progressive paced run to exhaustion without prior warm up elicits VO2max within 4 minutes : original research articleSource: International SportMed Journal 12, pp 68 –73 (2011)More Less
Background: In heavy exercise, preceded by adequate warm-up, VO2max can be attained within one minute, but when warm up is restricted VO2max would not be elicited in that time span.
Research question: How quickly VO2max can be achieved without prior warm up?
Methods: Eight professional male soccer players performed two tests to exhaustion. The field test consisted of two laps on a wood-chip track. The first lap was performed at 50% of the self-estimated maximal performance capacity, the first 200m of the 2nd lap at 70%, followed by an all out sprint. The incremental treadmill test started at a speed of 9km/h, velocity was increased by 1km/h every 1 minute (inclination of 1%). VO2, ventilation and heart rate were measured with a portable spirometric-telemetric device (Oxycon mobile, Germany).
Results: VO2max in the field test was achieved after 230±17s. When using 15s averages of breath-by-breath data collection in the field test VO2max values did not differ between the field and the lab test (61.0 ±2.5 vs. 61.1 ±2.2ml/min/kg, p=0.944). Values were highly correlated (r=0.857, p=0.007) with a standard error of estimation (SEE) of 0.9ml/min/kg.
Conclusions: Without previous warm up and with a progressive pacing strategy, VO2max can be elicited in 230 ±17s. VO2max was reached only at the very end of the run so that only the last 15s of the breath-by-breath data collection reflected the complete VO2 response. Results suggest that 180s of an intensive run (i.e. near the ventilatory threshold) is sufficient to allow VO2max achievement with an all-out effort thereafter.
Injuries to football (soccer) referees during matches, training and physical tests : original research articleSource: International SportMed Journal 12, pp 74 –84 (2011)More Less
Research question: The aim of this study was to analyze situations where professional football (soccer) referees suffer injuries.
Type of study: The study was designed as a retrospective survey which included 200 male soccer referees officiating in the Paraná's Football Championship (First and second divisions; 2005-2006 season) (Paraná-Brazil).
Methods: The referees completed a questionnaire on their referee qualifications, time spent in training and at matches, career history of musculoskeletal injuries caused by physical tests, training or refereeing.
Results: Ninety-five (95) injuries were identified as follow: 60% (57) occurred during physical training, 27% (26) during the physical tests, and 13% (12) during refereeing. Therefore most of the injuries happened during physical training. However, when the incidence rate of injuries by 1000 hours was calculated it was observed that the greatest incidence of injury occurred during the physical tests: 94.53 injuries per 1000 testing hours (95% CI, 62.1-126.9), p<0.001 when compared with training and refereeing. The total number of injuries was 95, where 78% were strains, 14% sprains and 6% fractures. Some referees suffered more than one type of injury. It was also possible to determine that these referees trained 3.7 ± 1.6 times a week and these training sessions were 60.3 ± 29.7 minutes long.
Conclusions: Soccer referees receive the highest incidence of injuries during the pre-season official physical tests, and were injured in the same proportion during official matches and training sessions. Muscle strains and ligament sprains were the most common injuries observed.
Source: International SportMed Journal 12, pp 85 –91 (2011)More Less
Background: Referees play a crucial role in soccer, although relevant key aspects of their physiological performance remain uncertain.
Research question: To describe the physiological profile of national-level Spanish soccer referees.
Type of study: Descriptive study.
Methods: Twenty-two male referees (age: 26.0 ± 4.9 years; height: 1.76 ± 0.08m; body mass: 76.3 ± 13.1kg; body mass index: 24.4 ± 2.8kg·m-2) were the participants of the study. Referees were subjected to a medical examination to determine their basal cardiovascular, haematological, pulmonary function and echocardiographical profile. Complementarily, the referees carried out an incremental maximal treadmill test and two field tests: a repeated sprint (6 x 40 m/90s recovery) and a running test (fastest time to complete 2000m).
Results: The left ventricular mass index averaged 122.3 ± 23.6g·m-2. Mean oxygen uptake (VO2max) averaged 48.7 ± 4.3ml·kg·min-1. Mean time during the repeated sprint test was 5.53 ± 0.21s, while mean time to complete the endurance test was 7 min 43s.
Conclusion: The physiological profile of national-level Spanish soccer referees reveals moderate aerobic cardiac adaptations to training and match officiating. As match demands are relative to the standard of competition, the referees should increase their physiological parameters to be able to cope with the demands imposed by the players.
Alteration in EMG during a graded treadmill exercise test after 3 days recovery from angioplasty in a patient with peripheral vascular disease : case reportSource: International SportMed Journal 12, pp 92 –103 (2011)More Less
Peripheral vascular disease limits exercise performance due to claudication pain, which is believed to originate from ischemia and increased blood lactate concentrations. However, no research has investigated the relationship between muscle activity, claudication pain and functional capacity. We report on a patient with a single tight stenosis of the femoral artery treated by performing percutaneous transluminal angioplasty. We measured muscle activity, exercise performance and other physiological variables before and 3 days after angioplasty. The patient performed maximal voluntary contractions prior to walking on the treadmill until exhaustion using the graded treadmill exercise test (GTET) protocol. Electromyography, heart rate, brachial blood pressure, rating of perceived exertion, pain score, oxygen consumption and blood lactate concentrations were measured during both trials. Muscle activity in the diseased leg was found to increase after angioplasty, with an increase in functional capacity and decrease in claudication pain. His physiological variables and force outputs improved after angioplasty; however, the blood lactate concentrations were low ranging between 2.00-1.75mmol.l-1 before angioplasty and 1.75-1.50mmol.l-1 after angioplasty. This case report demonstrates the change in muscle activity once blood flow is restored to the affected limb. We encourage clinicians and researchers to be attentive to the probable alteration in muscle activity and the role it plays in these patients' functional capacity and claudication pain. The findings of this study present possible usage for EMG in this patient population, 1) used as a additional screenings tool to objectively measure when the occlusion affects neuromuscular function and if so then angioplasty intervention could be justified; 2) as a monitoring tool of neuromuscular function during and after rehabilitation 3) possibly be used as a screening tool for re-occlusions.