Acute effects of two different initial heart rates on testing the Repeated Sprint Ability in young soccer players

AIM

The aim of this paper was to investigate the acute effects of two different initial heart rates intensities when testing the repeated sprint ability (RSA) performances in young soccer players.

METHODS

Since there are many kinds of pre-match warm-ups, we chose to take as an absolute indicator of internal load the heart rate reached at the end of two different warm-up protocols (60 vs. 90% HRmax) and to compare the respective RSA performances. The RSA tests were performed on fifteen male soccer players (age: 17.9±1.5 years) with two sets of ten shuttle-sprints (15+15 m) with a 1:3 exercise to rest ratio, in different days (randomized order) with different HR% (60 & 90% HRmax). In order to compare the different sprint performances a Fatigue Index (FI%) was computed, while the blood lactate concentrations (BLa-) were measured before and after testing, to compare metabolic demand.

RESULTS

Significant differences among trials within each sets (P<0.01) were found. Differences between sets were also found, especially comparing the last five trials for each set (Factorial ANOVA; P<0.01), effect size values confirming the relevance of these differences. Although the BLa- after warm-up was higher (36%) between 90% vs. 60% HRmax, after the RSA test the differences were considerably low (7%).

CONCLUSION

Based on physiological information's this methodological approach (testing with initial 90%HRmax) reflects more realistically the metabolic background in which a soccer player operates during a real match. This background may be partially reproduced by warming up protocols that, by duration and metabolic commitment, can reproduce conveniently the physiological conditions encountered in a real game (e.g. HRmax≈85-95%; BLa->4 mmol/L(-1)).

The influence of music on exercise in a group of sedentary elderly women: an important tool to help the elderly to stay active

AIM

The aim of this study was to verify how listening to instrumental asynchronous music, with tempo of 90 bpm, can affect the aerobic physical performance in elderly women engaged in a continuous and constant exercising, predominantly aerobic, consisting of walking routines.

METHODS

Twenty women (N.=20, age=75.8±4.2 years) volunteered to the study and underwent a six-week period of physical exercising. All women were previously sedentary, as they had not trained systematically within the last 5 years. The experimental group (Eg=10) performed all the exercise sessions and tests listening to music. The control group (Cg=10) performed the same program without listening to music. Total distances covered, heart rates before and after the tests and the rates of perceived exertion (RPE) were measured.

RESULTS

Significant differences between groups (P<0.01) were found in RPE. No statistically significant differences were observed in total distances covered and heart rates, although there was an increase of 9.83% in the total distance covered by the Eg compared to the Cg, in accordance with other previous researches.

CONCLUSION

The results are in line with those reported by other authors in different populations and ages, confirming that music may be considered an important tool in supporting elderly people involved in physical exercising.

Footstep manipulation during uphill running

The present study investigated the effects of step frequency manipulation during training on slopes (2%) on biomechanical parameters at Iso-Efficiency Speed (without increasing the metabolic demand). 24 male marathon runners were randomly allocated to one of 2 training groups for 3 weeks: step frequency manipulation group (SFM, n=12) and free step frequency group (SFF, n=12). Lower limb kinematic parameters were measured before and after the 3 weeks training. The SFM group increased step length 4.30% (p<0.001), flight time 29.48% (p<0.001) and decreased contact time 14% (p<0.01). These findings coincide with characteristics of better running performances. The SFF group did not elicit such results. The results from the study could help coaches to devise training methods which could improve an athlete's performance through increasing step length. The method provided may aid faster race times for athletes.

Kinematic analysis of soccer players in shuttle running

The intermittent shuttle running test is mainly used within soccer to assess aerobic power. For this reason we studied kinematic parameters and heart rate at both an increasing speed, [Yo-Yo Endurance Lv 1 (Y₁)] and at constant velocity [95% maximal aerobic velocity (MAV(95%))]. 12 soccer players were selected for this study. A high-speed digital camera (210 Hz) was used to record motion; Dartfish5.5Pro was used to perform 2D video analysis and heart rate was also recorded and computed during the test. The parameters considered (baseline measures with respect to the end of each test) in this study were: step length (SL), contact time (CT) and heart rate (HR). SL: 40% in Y1 and -22% in MAV(95%). CT: -31% in Y1 and 29% in MAV(95%). HR: increased 96% in Y1 and 17% in MAV(95%). These results highlight 2 different neuromechanical strategies adopted under fatigued conditions. In light of the clear changes of the CT in MAV(95%) (29%) and with respect to the moderate changes in HR (17%) it is clear that the CT is the most important parameter, as it experiences greater adaptations associated with neuromuscular patterns, under a fatigued condition as opposed to HR.

Effect of different pushing speeds on bench press

The purpose of this study was to investigate the effect on muscular strength after a 3-week training with the bench-press at a fixed pushing of 80-100% maximal speed (FPS) and self-selected pushing speed (SPS). 20 resistance-trained subjects were divided at random in 2 groups differing only regarding the pushing speed: in the FPS group (n=10) it was equal to 80-100% of the maximal speed while in the SPS group (n=10) the pushing speed was self-selected. Both groups were trained twice a week for 3 weeks with a load equal to 85% of 1RM and monitored with the encoder. Before and after the training we measured pushing speed and maximum load. Significant differences between and within the 2 groups were pointed out using a 2-way ANOVA for repeated measures. After 3 weeks a significant improvement was shown especially in the FPS group: the maximum load improved by 10.20% and the maximal speed by 2.22%, while in the SPS group the effect was <1%. This study shows that a high velocity training is required to increase the muscle strength further in subjects with a long training experience and this is possible by measuring the individual performance speed for each load.

Throwing velocity and kinematics in elite male water polo players

AIM

Fifty-three members of the Italian Men Water Polo Team were filmed using two synchronized cameras, while they were shooting a goal. Considering the differences in body mass, height, training strategies and the technical-tactical features of the players, the aims of this study were to employ video-analysis techniques in order to investigate selected kinematic parameters in water polo throwing, and to provide comprehensive quantitative information on the throwing movement in relation to the different team player positions.

METHODS

Video analysis was used to estimate the elbow angle at release, the shoulder angle at follow through, the back and head height at ball release, trunk rotation angle and ball velocity at release.

RESULTS

Ball release velocities ranged from 21.0 to 29.8 m/s (average value 25.3±1.4 m/s), for field players. Goal keepers show the lowest team values (average 21.7±0.3 m/s). Similar to previous study results, ball release was typically reached just prior to the elbow approaching full extension (151.6±3.6°), and the follow through shoulder angle was 143±5.9°.

CONCLUSION

No significant statistical difference was recorded between injured and non-injured athletes. No positive association was demonstrated between physical characteristics (body mass and height) and ball velocity.

Effect of maximal aerobic power on match performance in elite soccer referees

The aim of this study was to verify whether referees' maximal aerobic power could influence competitive match exercise intensity. Eight elite-level referees (mean +/- SD age, 37.6 +/- 3.4 years) were each observed during 2 Serie A matches (n = 16), and the mean of each match activity was used for analysis. Match activities were monitored with encoder-equipped cameras. .V(O)(2)max was assessed under field conditions with a portable device during a progressive multistage protocol. The .V(O)(2)max of each subject was expressed in absolute terms (.V(O)(2)max(ab), L.min(-1)), relative terms (.V(O)(2)max (rel), ml.kg(-1).min(-1)), and independent from body mass (.V(O)(2)max (ind), ml.kg(-0.75).min(-1)). Significance was set at p < or = 0.05 for all measurements. Total distance covered during the match correlated significantly with .V(O)(2)max (ind) (r = 0.77) and .V(O)(2)max (ab) (r = 0.87). .V(O)(2)max (ind), .V(O)(2)max (rel), and .V(O)(2)max (ab) correlated negatively (p < 0.05) with the time spent standing still during the match (r = -0.90, -0.85, and -0.86, respectively, p < 0.05). During the first half of the match, referees with higher levels of .V(O)(2)max (rel) (r = 0.93, p < 0.05) and .V(O)(2)max (ind) (r = 0.90, p < 0.05) were able to cover more distance at medium intensity. In the second half of the match, medium-intensity distance and low-intensity time correlated significantly (p < 0.05) with .V(O)(2)max (ab) (r = 0.76) and .V(O)(2)max (rel) (r = 0.75), respectively. The results demonstrate the positive influence of .V(O)(2)max in determining both the total amount of distance covered and the exercise intensity during a game. Higher levels of .V(O)(2)max may provide referees the opportunity to be more active and therefore closer to the action on the field during the game.

Physiological load imposed on elite soccer referees during actual match play

BACKGROUND

The aim of this study as to describe the work-rate profile and cardiovascular stress of Italian high level soccer referees (n = 18). METHODS.

EXPERIMENTAL DESIGN

The referees were examined during official games of the 1992-1993 first division Italian championship (serie A).

PARTICIPANTS

subjects were all experienced top level referees enrolled in the CAN (Commissione Arbitri Nazionali) and thus officiating in the serie A e B Italian championships. Mean age of the referees considered here was 37.5 +/- 2.14 years.

MEASURES

heart rates were monitored by short-range radio telemetry. Match analysis was performed with methodologies similar to that reported by Ohashi et al. (1988).

RESULTS

Average match distance was 11376 +/- 1600 m (7818-13063) and no overall differences were observed between halves (p > 0.05). Nevertheless less distances were covered running backward and side-wards during the second half compared to the first half (p < 0.05). Referees, on average, covered 41.7% of the whole match distance at speeds faster than 13.1 km x h(-1). Heart rates attained 89.1% of the estimated maximal over the duration of a full game and no difference was observed between halves (p = 0.72). Mean heart rates of the first 15 min of play were lower than the other two sections of the first half (p < 0.05).

CONCLUSIONS

Match analysis revealed the intermittent nature of the referees' activities. Their intensity varied from situation to situation, frequently reaching near maximal intensity. However, sprint bouts never lasted for more than few seconds (2-4 sec). Top level soccer refereeing places high physiological demands on the official thus specific training and fitness assessment are needed.