Did the quarantine period of covid-19 interfere with the physical demands of central referees and assistants in professional soccer in a high level competition in Brazil?

Objective: This study compares the performance demanded from central referees and soccer assistants during professional games before and after the quarantine of COVID-19 during the same competition. Equipment and methods: Ten central referees and 19 assistants were monitored. Using a watch with Global Positioning System technology and a heart rate monitor, data were obtained of the distance they moved and information on their heart rate. A game before the quarantine period was compared to a game played 128 days after the quarantine period. These participants represented all the referees who played at least one game in the pre- and post-quarantine period of the same high-level competition in Brazil. Results: The results indicated that the total distance, average, and maximum heart rate did not present significant differences between the pre-and post-quarantine time of the central and assistant referees, except for the distance covered by the assistant referees in the second half, which was significantly greater in the post-quarantine period (Δ% = 6.27; P = 0.034). In conclusion, the central referees and assistants' performance was not affected after the 128-day quarantine period compared to the traditional transition period between the 37-day seasons.

Objectif: Cette étude compare les performances exigées des arbitres centraux et des assistants de football lors de matchs professionnels avant et après la mise en quarantaine pour COVID-19 lors de la même compétition. Matériel et méthodes: Dix arbitres centraux et 19 assistants ont été suivis. À l'aide d'une montre dotée de la technologie Global Positioning System et d'un moniteur de fréquence cardiaque, des données ont été obtenues sur la distance parcourue et des informations sur leur fréquence cardiaque. Un jeu avant la période de quarantaine a été comparé à un jeu joué 128 jours après la période de quarantaine. Ces participants représentaient tous les arbitres qui ont joué au moins un match dans la période pré et post-quarantaine de la même compétition de haut niveau au Brésil. Résultats: Les résultats ont indiqué que la distance totale, la fréquence cardiaque moyenne et maximale ne présentaient pas de différences significatives entre le temps avant et après la quarantaine des arbitres centraux et assistants, à l'exception de la distance parcourue par les arbitres assistants en seconde période, qui était significativement plus élevée dans la période post-quarantaine (Δ % = 6,27 ; p = 0,034). En conclusion, les performances des arbitres centraux et des assistants n'ont pas été affectées après la période de quarantaine de 128 jours, comparativement à la période de transition traditionnelle entre les saisons de 37 jours.

Effects of Single Vs. Multiple Sets during 10 Weeks of Water-based Resistance Training on Neuromuscular Adaptations in Young Women.

This study aims to analyze the neuromuscular adaptations of sedentary young women between water-based resistance training performed with single and multiple sets. 66 women (24.72±4.33 years old) were randomly divided into 2 training groups: SS (single set of 30 s) and MS (3 sets of 30 s). Both groups performed 2 sessions per week for 10 weeks. One repetition maximal test (1RM), muscle endurance test (maximal repetitions at 60% 1RM) and muscle power test (squat and countermovement jump performance) were evaluated at pre- and post-training. To compare neuromuscular variables, a repeated measures ANOVA with a group factor (α=0.05) was used. Both groups showed significant increases in 1RM (SS: 14.59%; MS 14.86%), in 60% 1RM (SS: 31.23%; MS: 37.37%), in SJ (SS: 10.9%; MS: 8.3%) and CMJ (SS: 9.1%; MS: 6.8%), without difference between groups. There can be concluded that young and sedentary women presented improvements in different expressions of strength after 10 weeks of training, regardless the volume of training.

Oxygen uptake, muscle activity and ground reaction force during water aerobic exercises.

This study aimed to compare the oxygen uptake (VO2), the muscle activity of lower limbs, and the vertical ground reaction force (V-GRF) of women performing water aerobic exercises at different intensities. 12 young women performed the experimental protocol, which consisted of 3 water exercises (stationary running [SR], frontal kick [FK] and cross country skiing [CCS]) at 3 intensities (first and second ventilatory thresholds and maximum effort). A two-way repeated measures ANOVA was used. Regarding VO2, different responses between intensities (p<0.001) were found, and values between exercises were similar. For electromyographic activity (EMG), differences between intensities for all muscles (p<0.001) were found. Greater EMG signals were observed in the FK compared to SR for rectus femoris, semitendinosus, vastus lateralis and biceps femoris muscles (p<0.05). Regarding V-GRF, there was an increase in the V-GRF at greater intensities compared to the first ventilatory threshold (p=0.001). In addition, lower values were found during CCS compared to the SR and FK exercises (p<0.001). Thus, greater cardiorespiratory and neuromuscular responses were observed with increasing intensity. Exercises such as CCS could be used to attenuate the V-GRF; if the purpose is to reduce the muscular activity of lower limbs at a specific intensity, SR could be recommended.

Effects of intra-session exercise sequence during water-based concurrent training.

The aim was to investigate the effects of the intra-session exercise order during water-based concurrent training on the neuromuscular adaptations in young women. 26 women (25.1±2.9 years) were placed into 2 groups: resistance prior to (RA) or after (AR) aerobic training. Subjects performed resistance (sets at maximal effort) and aerobic training (exercises at heart rate corresponding to the second ventilatory threshold) twice a week over 12 weeks, performing both exercise types in the same training session. Upper (elbow flexion) and lower-body (knee extension) one-repetition maximum test (1RM) and peak torque (PT) were evaluated. The muscle thickness (MT) of upper (sum of MT of biceps brachii and brachialis) and lower-body (sum of MT of vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris) was determined by ultrasonography. Moreover, the maximal electromyographic activity (EMG) of upper (biceps brachii) and lower-body (sum of EMG of vastus lateralis and rectus femoris) was measured. Both RA and AR groups increased the upper and lower-body 1RM and PT, while the lower-body 1RM increases observed in the RA was greater than AR (43.58±14.00 vs. 27.01±18.05%). RA and AR showed MT increases in all muscles evaluated, while the lower-body MT increases observed in the RA were also greater than AR (10.24±3.11 vs. 5.76±1.88%). There were increases in the maximal EMG of upper and lower-body in both RA and AR, with no differences between groups. Performing resistance prior to aerobic exercise during water-based concurrent training seems to optimize the lower-body strength and hypertrophy.

Determining the anaerobic threshold in water aerobic exercises: a comparison between the heart rate deflection point and the ventilatory method.

AIM: The aim of this study was to compare the cardiorespiratory variables corresponding to the anaerobic threshold (AT) between different water-based exercises using two methods of determining the AT, the heart rate deflection point and ventilatory method, and to correlate the variables in both methods. METHODS: Twenty young women performed three exercise sessions in the water. Maximal tests were performed in the water-based exercises stationary running, frontal kick and cross country skiing. The protocol started at a rate of 80 cycles per minute (cycle.min-1) for 2 min with subsequent increments of 10 cycle.min-1 every minute until exhaustion, with measurements of heart rate, oxygen uptake and ventilation throughout test. After, the two methods were used to determine the values of these variables corresponding to the AT for each of the exercises. Comparisons were made using two-way ANOVA for repeated measures with Bonferroni's post hoc test. To correlate the same variables determined by the two methods, the intra-class correlation coefficient test (ICC) was used. RESULTS: For all the variables, no significant differences were found between the methods of determining the AT and the three exercises. Moreover, the ICC values of each variable determined by the two methods were high and significant. CONCLUSION: The estimation of the heart rate deflection point can be used as a simple and practical method of determining the AT, which can be used when prescribing these exercises. In addition, these cardiorespiratory parameters may be determined performing the test with only one of the evaluated exercises, since there were no differences in the evaluated variables.

Correlations between serum hormones, strength and endurance in healthy elderly South-American men.

AIM: Declines in muscular strength resulting from reduced serum anabolic hormones and neural activity may influence the reduction in aerobic capacity in older men. However, there has been little investigation into the relationship between steroid hormones and muscular strength, as well as endurance capacity in elderly subjects. The purpose of this study was to investigate the possible relationship between serum steroid hormones, strength and aerobic performance in older men. METHODS: Twenty-eight aged men (65±4 years) were evaluated in dynamic strength (one repetition maximum test), isometric strength (maximal voluntary contraction) and rate of force development. Peak oxygen uptake and maximal workload were determined during a ramp protocol on a cycle ergometer. In addition, blood samples were taken to determine basal cortisol, total and free testosterone. RESULTS: No correlations were found between steroid hormonal concentrations and the performance parameters investigated. CONCLUSION: Our results suggest that single measurements of steroids hormones concentrations are not related to the strength and endurance capacity of healthy South-American elderly men.

Vertical ground reaction force during water exercises performed at different intensities.

The aim of the present study was to compare the peak vertical ground reaction force (V-GRF(peak)) and impulse of women performing water aerobic exercises at different intensities in aquatic and dry land environments. 15 young women performed 1 session in each environment consisting of 3 water aerobic exercises (stationary running, frontal kick and cross country skiing) performed at 3 cadences (first ventilatory threshold, second ventilatory threshold and maximum effort, as determined during exercise in water) in a randomized order. 2-way and 3-way repeated measures ANOVA were used to analyze the impulse and V-GRF(peak), respectively. Significantly lower values of V-GRF(peak) and impulse (p<0.001) were observed for the aquatic environment. Significant differences were observed among all cadences for V-GRF(peak) and impulse (p<0.001) in both environments except for the V-GRF(peak) between the cadences corresponding to the second ventilatory threshold and maximum effort in the aquatic environment. In addition, significantly lower V-GRF(peak) values in the aquatic environment were found for cross country skiing compared to the other exercises (p<0.001). Thus, water exercises are safe for people that need to minimize vertical ground reaction force; however, an important issue to be considered during water aerobics training is the exercise and intensity to be prescribed.

3 Different types of strength training in older women.

The objective of the present study was to evaluate and compare the neuromuscular, morphological and functional adaptations of older women subjected to 3 different types of strength training. 58, healthy women (67 ± 5 year) were randomized to experimental (EG, n=41) and control groups (CG, n=17) during the first 6 weeks when the EG group performed traditional resistance exercise for the lower extremity. Afterwards, EG was divided into three specific strength training groups; a traditional group (TG, n=14), a power group (PG, n=13) that performed the concentric phase of contraction at high speed and a rapid strength group (RG, n=14) that performed a lateral box jump exercise emphasizing the stretch-shortening-cycle (SSC). Subjects trained 2 days per week through the entire 12 weeks. Following 6 weeks of generalized strength training, significant improvements occurred in EG for knee extension one-repetition (1RM) maximum strength (+19%), knee extensor muscle thickness (MT, +15%), maximal muscle activation (+44% average) and onset latency ( -31% average) for vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) compared to CG (p<0.05). Following 6 more weeks of specific strength training, the 1RM increased significantly and similarly between groups (average of +21%), as did muscle thickness of the VL (+25%), and activation of VL (+44%) and VM (+26%). The onset latency of RF (TG=285 ± 109 ms, PG=252 ± 76 ms, RG=203 ± 43 ms), reaction time (TG=366 ± 99 ms, PG=274 ± 76 ms, RG=201 ± 41 ms), 30-s chair stand (TG=18 ± 3, PG=18 ± 1, RG=21 ± 2) and counter movement jump (TG=8 ± 2 cm, PG=10 ± 3 cm, RG=13 ± 2 cm) was significantly improved only in RG (p<0.05). At the end of training, the rate of force development (RFD) over 150 ms (TG=2.3 ± 9.8 N·s(-1), PG=3.3 ± 3.2 N·s(-1), RG=3.8 ± 6.8 N·s(-1), CG=2.3 ± 7.0 N·s(-1)) was significantly greater in RG and PG than in TG and CG (p<0.05). In conclusion, rapid strength training is more effective for the development of rapid force production of muscle than other specific types of strength training and by consequence, better develops the functional capabilities of older women.

Concurrent training with different aerobic exercises.

The aim of the present study was to compare the effects of using different intensities and types of aerobic exercise (i. e., cycle ergometer or running) during concurrent training on neuromuscular adaptations. A total of 44 young women were randomly assigned to 1 of 4 groups: concurrent strength and continuous running training (SCR, n=10), concurrent strength and interval running training (SIR, n=11), concurrent strength and continuous cycle ergometer training (SCE, n=11), or strength training only (STO, n=12). Each group trained twice a week during 11 weeks. The following strength measurements were made on all subjects before and after training period: maximal strength (1RM) in knee extension, bench press and leg press exercises; local muscular endurance (number of repetitions at 70% of 1 RM) in knee extension and bench press exercises; and isometric and isokinetic peak torque of knee extension. There were significant increases in the upper and lower-body 1 RM, isometric and isokinetic peak torque in all training groups (p<0.001), with no differences between groups. The present results suggest that in young women, concurrent training performed twice a week promotes similar neuromuscular adaptations to strength training alone, regardless of the type and the intensity in which the aerobic training is performed.

Cardiorespiratory and neuromuscular responses during water aerobics exercise performed with and without equipment.

The aim of the study was to compare the cardiorespiratory and neuromuscular responses to water aerobics exercise performed with and without equipment. 15 women performed stationary jogging combined with elbow flexion/extension without equipment, with water-drag forces equipment and with water-floating equipment, at 2 submaximal cadences and at maximal cadence. Heart rate, oxygen uptake and electromyographic signal from biceps brachii, triceps brachii, biceps femoris and rectus femoris were collected during the exercise. The heart rate and oxygen uptake showed significantly higher values during the execution of the water aerobics exercise with either equipment compared to the execution without equipment. In addition, significant difference was found between submaximal cadences. For neuromuscular responses, no significant differences were found between the submaximal cadences for all muscles analyzed; however, significant differences were found between these submaximal cadences and the maximal cadence. Similarly, the results showed no significant differences between the execution of the exercise with or without equipment, except in the muscle activation of triceps brachii and biceps femoris, which was higher when using water-floating and water-drag forces equipment, respectively. In conclusion, the water aerobics exercise presented higher cardiorespiratory responses with equipment and also increased the cadence of execution. Nevertheless, neuromuscular responses were higher only at maximal cadence.

Non-steroidal anti-inflammatory use in the XV Pan-American Games (2007).

BACKGROUND: non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used in sports medicine to reduce time of incapacity. OBJECTIVE: to describe the frequency of NSAIDs use by athletes in the XV Pan-American Games. METHODS: all athletes who were tested by the anti-doping control filled a form. The voluntarily declared medications were recorded and categorised according to sport modality, sex, region and control situation according to the World Anti-Doping Agency. RESULTS: among the 1261 athletes tested (231 out-competition (OC) and 1030 in-competition (IC); 733 men and 528 women), 63% reported use of drugs, NSAIDs being the most frequently (64% of users) used medications. The use of medications was not significantly different between sexes or among different regions of the world. The number of users of only one type of NSAID was higher than those who used more than one type of NSAIDs or a combination with analgesics (335 vs 168 cases). IC reports presented higher use of NSAIDs than OC. CONCLUSION: athletes tested by the anti-doping control of the XV Pan-American Games reported a high frequency of NSAIDs use. The frequent utilisation in competition suggests that these medications might be used as ergogenic aid.

Physiological effects of concurrent training in elderly men.

The aim of the present study was to investigate the effects of concurrent strength and endurance training on neuromuscular and hormonal parameters in elderly men. 23 healthy men (65±4 years) were randomly assigned to 1 of 3 groups: concurrent (CG, n=8), strength (SG, n=8) or endurance group (EG, n=7). The programs consisted, of strength training, endurance training on a cycle ergometer or a combination of both in the same session 3 times per week over a duration of 12 weeks. Subjects were evaluated on parameters related to muscle strength, muscle activation and serum hormones. There were significant increases in lower-body strength in all groups (P<0.05), with higher increases in SG (67%) than CG (41%) and both were higher than EG (25%) (p<0.01). Only SG and CG increased upper-body strength (p<0.01), with no significant difference between the 2 groups. Furthermore, there were significant decreases in free testosterone in EG after training. Significant increases in isometric strength and maximal muscle activation (p<0.05) as well as decreases in the submaximal muscle activation to the same load, were only seen in SG (p<0.05). The present results suggest that the interference effect observed due to concurrent strength and endurance training could be related to impairment of neural adaptations.

Cardiorespiratory responses to stationary running at different cadences in water and on land.

AIM: The aim of the current study was to analyze the heart rate (HR), oxygen uptake (V.O(2)), and percentage of maximal HR (%HR(max)) and V.O(2) (%V.O(2max)) responses to stationary running exercise performed at different cadences on land (LA) and in water (WA). METHODS: The sample comprised 12 apparently healthy women (mean age 22.33+/-0.57 years). The exercise was performed in WA and LA environments (interval of 2 hours) at submaximal cadences of 60, 80 and 100 bpm for a period of 4 min at each cadence (interval of 5 min). HR and V.O(2) data were collected using a Polar S610TM and Aerosport KB1-C gas analyzer, respectively. The data were analyzed using factorial ANOVA for mixed models, Tukey's post hoc and Pearson's correlation test, with P<0.05 (SPSS version 13.0). RESULTS: Significant differences were found between the environments for all variables (HR, V.O(2), %HR(max) and %V.O(2max): P<0.001), with higher values for LA. Significant differences were found between the cadences for all variables (HR, V.O(2), %HR(max) and %V.O(2max): P<0.001). The effect of the interaction environment cadence was only significant for %HR(max) (P=0.041). The correlations between HR and V.O(2) (WA: r=0.857; P<0.001 and LA: r=0.556; P<0.001) and %HR(max) and %V.O(2) (WA: r=0.860; P<0.001 and LA: r=0.798; P<0.001) exhibited high and significant correlation coefficient values, especially for WA, suggesting that variable increased linearly with increases in cadence. CONCLUSIONS: The results suggest that cardiorespiratory responses to stationary running exercise are lower in WA, though they can be maximized by increasing the execution cadence.