Recovery kinetics of knee flexor and extensor strength after a football match

© 2015 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0128072We examined the temporal changes of isokinetic strength performance of knee flexor (KF) and extensor (KE) strength after a football match. Players were randomly assigned to a control (N = 14, participated only in measurements and practices) or an experimental group (N = 20, participated also in a football match). Participants trained daily during the two days after the match. Match and training overload was monitored with GPS devices. Venous blood was sampled and muscle damage was assessed pre-match, post-match and at 12h, 36h and 60h post-match. Isometric strength as well as eccentric and concentric peak torque of knee flexors and extensors in both limbs (dominant and non-dominant) were measured on an isokinetic dynamometer at baseline and at 12h, 36h and 60h after the match. Functional (KFecc/KEcon) and conventional (KFcon/KEcon) ratios were then calculated. Only eccentric peak torque of knee flexors declined at 60h after the match in the control group. In the experimental group: a) isometric strength of knee extensors and knee flexors declined (P<0.05) at 12h (both limbs) and 36h (dominant limb only), b) eccentric and concentric peak torque of knee extensors and flexors declined (P<0.05) in both limbs for 36h at 60°/s and for 60h at 180°/s with eccentric peak torque of knee flexors demonstrating a greater (P<0.05) reduction than concentric peak torque, c) strength deterioration was greater (P<0.05) at 180°/s and in dominant limb, d) the functional ratio was more sensitive to match-induced fatigue demonstrating a more prolonged decline. Discriminant and regression analysis revealed that strength deterioration and recovery may be related to the amount of eccentric actions performed during the match and athletes' football-specific conditioning. Our data suggest that recovery kinetics of knee flexor and extensor strength after a football match demonstrate strength, limb and velocity specificity and may depend on match physical overload and players' physical conditioning level.Published versio

Occurrence of acute lower limb injuries in artistic gymnasts in relation to event and exercise phase

Objectives: To record the incidence of lower limb injuries (acute and overuse syndromes) in Greek artistic gymnasts in relation to the event and exercise phase. Methods: A total of 162 gymnasts (83 male and 79 female athletes) participating in the Greek artistic gymnastic championships were observed weekly for the 1999–2000 season. Results: Ninety three (61.6%) acute injuries and 58 (38.4%) overuse syndromes were recorded. The most common anatomical location was the ankle (69 cases, 45.7%), followed by the knee (40 cases, 26.5%). The rate of mild injuries was 26.6% (25 cases), that of moderate injuries was 44% (41 cases), and that of major injuries was 29% (27 cases). The incidence of injury to the ankle and knee was significantly higher in the floor exercise, especially during the landing phase, than in the other events. Conclusions: By its nature, gymnastics predisposes to acute injuries, but up to 75% are mild or moderate. Special attention should be paid to the floor exercise, especially the landing phase

Examining psychological factors during injury rehabilitation

The aim of this study was to examine the effectiveness of goal setting on performance and on a number of psychological variables such as self-efficacy, pretesting anxiety, and self-satisfaction during an injury rehabilitation program. An experimental group (n = 20) and a control group (n = 17) of injured physical education students were studied. Both groups underwent a 3-week quadriceps strengthening program on an isokinetic dynamometer, with the experimental group setting specific personal goals in each training session. The experimental group improved in performance significantly more than the control group. Although both groups exhibited an increase in self-efficacy and a decrease in pretesting anxiety, only the experimental group had an increase in self-satisfaction with performance. Results confirm that incorporating goal setting in the rehabilitation process enhances rehabilitation results

Factors related to the incidence of injuries&apos; appearance to volleyball players

The purpose of this study was to investigate the external risk factors that contribute to sports injuries experienced by Volleyball players. 114 Greek Volleyball players (61 male and 53 female) who participate in the Volleyball Championship including the A1 and A2 national division and the local championships, age 22.77 (SD = 4.85) participated in this study. A questionnaire survey was used for data collection purposes and the interviews were conducted on a personal level. Of the 114 volley ball players (94.5 response rate), reported 363 injuries, during a total exposure time of 34200 h/year for 5 years, representing an overall incidence of 0.63 injuries per player. The majority of the injuries were located in the ankle region (51.3%), followed by the knee (18.2%) and the back (12.4%). Most injuries (58.1%) were classified as being of moderate severity. Most injuries occurred during training (52.3%), and the 69.1% of them during the competitive season. The present study indicates that the risk of suffering an injury in volleyball is relatevly high therefore more researches are needed to accomplish in order practitioners and clinics prevent injuries in training period and competitions. © 2006 IOS Press. All rights reserved

Effective ways of restoring muscular imbalances of the rotator cuff muscle group: a comparative study of various training methods

Background: Many studies have compared different training methods for improving muscular performance, but more investigations need to be directed to the restoration of muscular imbalances. Objective: To determine the most effective training for altering strength ratios in the shoulder rotator cuff. Methods: Forty eight physical education students were randomly assigned to four groups (12 per group): (a) experimental group who carried out multijoint dynamic resistance training for shoulder internal and external rotation movement (pull ups or lat pull downs, overhead press, reverse pull ups, push ups) (MJDR group); (b) experimental group who exercised the same muscle group using dumbbells weighing 2 kg (isolated group); (c) experimental group who followed an isokinetic strengthening programme for the rotator cuff muscle group (isokinetic group); (d) control group who had no strength training. Testing was performed in the supine position with the glenohumeral joint in 90° of abduction in the coronal plane, with a range of motion of 0–90° of external rotation and 0–65° of internal rotation at angular velocities of 60, 120, and 180°/s. The test procedure was performed before and after the exercise period of six weeks. Results: One way analysis of variance found no differences between the groups for the initial tests. Analysis of variance with repeated measures showed that the strength ratios in all the experimental groups had altered after the exercise period, with the isokinetic group showing the most significant improvement. Conclusions: Isokinetic strengthening is the most effective method of altering strength ratios of the rotator cuff muscle

Different training programs for improving muscular performance in healthy inactive elderly

Abstract. The purpose of the present study was to determine whether a general conditioning (callisthenic exercise) versus a machine based resistance-training protocol or an isokinetic exercise program would be similarly effective in improving knee extension muscular performance in healthy inactive elderly. Fifty two individuals, 26 men and 26 women, were randomly assigned to one of four groups: control group (C, n = 10), the isokinetic strengthening group (ISO, n = 12), the multi-joint resistance training group (RES, n = 15) and the calisthenic exercised group (CAL, n = 15). The training protocol for the ISO included concentric isokinetic extension and flexion of the knee, for the RES included leg extension, leg curls and leg press and for the CAL included aerobic exercise accompanied with music, general calisthenics and activities targeted to reaction time and agility improvement. The isokinetic concentric testing method applied prior to and at the end of the training period to assess peak muscle torque of the right knee extensors. MANOVA repeated measures (2 × 4, time by treatment) revealed that at 60 • /s angular velocity there was statistically significant improvement in performance for the RES group in comparison to control group. At 180 • /s angular velocity the results revealed, statistically significant improvement in performance for the RES and ISO group also. In conclusion, in older adults isokinetic exercise and resistance training results in larger increases in strength compared with callisthenic exercise