International SportMed Journal - Volume 11, Issue 2, 2010
Volume 11, Issue 2, 2010
The efficacy of cryotherapy on recovery following exercise-induced muscle damage : invited review articleSource: International SportMed Journal 11, pp 258 –277 (2010)More Less
Cryotherapy is a popular recovery modality used to accelerate recovery from exercise-induced muscle damage (EIMD). However, there is equivocal evidence for the efficacy of the intervention. A computer-based literature search was undertaken. Primary research studies using healthy human participants were selected for the review. Cryotherapy interventions included ice massage, ice bag application, and cold water immersion of the limbs. EIMD was induced using high-velocity eccentric exercise protocols, repeated stretch shortening cycle exercise or intense training. Data were extracted on different methods of cold application and the effects on indirect markers of EIMD and functional recovery post-exercise. 13 studies were included. There were equivocal findings for the effects of cryotherapy on muscle soreness, range of movement (ROM), muscle function, and biochemical markers including plasma creatine kinase (CK) activity. Cryotherapy had no effect on post-exercise swelling or myoglobin levels. Decreases in selected pro- and anti-inflammatory cytokines, anabolic mediators, and catabolic markers were reported. Cryotherapy may have positive effects on the symptoms of delayed onset muscle soreness (DOMS); however, the influence on measurements of functional performance is unclear. There is currently inconclusive evidence to support the use of cryotherapy modalities in recovery from EIMD. Participants were generally healthy, physically active participants, and the application of these findings to enhancing recovery in elite athletes may be limited. Further studies are required to determine both acute and long-term effects of cryotherapy on recovery in elite athletes subjected to regular and intense training and competition.
Physical and technical activity of soccer players in the French First League - with special reference to their playing position : original research articleSource: International SportMed Journal 11, pp 278 –290 (2010)More Less
Background: The aim of this study was to analyze the physical and technical activities of elite soccer players from the French First League, according to their playing positions.
Methods: During the 2005-2006 season, 3540 professional soccer players' activities were recorded and analysed during competitive matches played by means of a semi-automatic video system (Amisco ©). Physical and technical variables were analyzed according to their specific playing positions. The players were classified into 6 positional roles: central defenders (CD), full-backs (FB), central defensive midfielders (CDM), wide midfielders (WM), central attacking midfielders (CAM), and forwards (FW). Match performance variables analysed included: (a) physical activity: total distance covered, distances covered at high-intensities both with and without possession of the ball; (b) technical actions: heading and ground duels, passing, time in possession and ball touches.
Results: The total distances covered ranged from 10425.9m to 12029.5m, with especially 235.4m to 290.4m in sprinting. In the offensive phase, FW covered ∼4 times greater total distances in sprinting than CD and FB (p <0.001). The technical analysis showed that the players had the possession of the ball between 55.5sec and 74.2sec per match played and they had no more than 2.2 ball touches per individual possession. More specifically, midfielders (CDM, WM and CAM) performed successful passes ranging from 75% to 78%, whereas lower values were found for the FW (71%) and CD (63%) respectively.
Conclusions: Soccer at the elite level requires that the players have a high aerobic capacity and that they are able to perform many high-intensity actions, especially the capacity for repeated sprints. Although these main findings showed the characteristics of French elite soccer, the players have to be skilful with their few ball possessions. In conclusion, elite soccer is characterized by the ability of the players to repeat high-intensity actions, but almost to be able to lose a small part of their ball possessions and to realize quickly the technical actions during the matches played.
Effects on muscle performance of two jumping and two cycling bouts separated by 60 minutes : original research articleSource: International SportMed Journal 11, pp 291 –300 (2010)More Less
Background: Exercise-induced changes in muscle force depend on metabolic fatigue, muscle damage, and low-frequency fatigue. As far as is known, no study has investigated how these types of fatigue manifest during a repeated bout of exercise shortly after the first bout. Research objective: To examine changes in muscle performance after two bouts of maximal jumping or cycling exercise with a short interval between bouts. Type of study: Experimental laboratory study. Methods: Men (n=10) performed two bouts of jumping (50 continuous jumps) or cycling (30s Wingate test) with a 60min rest between bouts and a one-month interval between jumping and cycling. The peak quadriceps muscle force evoked by electrical stimulation at 15Hz (P15) or 50Hz (P50) was measured before exercise and 2-, 30-, and 60min after exercise. Muscle soreness and creatine kinase activity were determined 48h after bout 2. Results: P15 and P50 decreased after the first bouts of jumping and cycling and did not recover to the pre-exercise level within 60min (P<0.05). Consequently, the second bout was performed with a still-depressed stimulation force. However, P15, P50, and the P15/P50 ratio did not decline more strongly after bout 2 than after bout 1. Conclusions: Two different types of exercise caused similar reductions in electrically evoked muscle performance within 60min of exercising. A second bout of jumping or cycling shortly (60min) after the first bout and before full muscle recovery did not exacerbate the impairment of muscle function.
Comparison of sagittal spinal curvatures and hamstring muscle extensibility among young elite paddlers and non-athletes : original research articleSource: International SportMed Journal 11, pp 301 –312 (2010)More Less
Background: Sagittal spinal curvatures may be influenced by specific and repetitive sport training.
Research question: To compare the sagittal spinal curvatures and hamstring muscle extensibility between paddlers and non-athletes. Type of study: descriptive and comparative. Methods: Participants: Sixty-five junior paddlers (23 female kayakers, 22 male kayakers and 20 male canoeists) and 44 non-athletes (control group: 22 males and 22 females) between 13-14 years. Main measures of outcome: Thoracic and lumbar angles while relaxed standing and in maximal forward bending with knees extended (sit and reach test) were measured with a Unilevel inclinometer. Hamstring muscle extensibility was also measured using the straight leg raise in both legs. Results: No differences were found in thoracic angle among groups in standing, except between females / males kayakers and females / males controls. Standing lumbar angle was greater in control groups than in their respective paddlers groups (p < 0.01). The paddlers reached greater lumbar and thoracic angles in the sit-and-reach tests than controls (p < 0.001). The paddlers reached similar straight leg raise angles than their respective control group. Conclusions: Specific and repetitive training of elite young paddlers does not influence thoracic standing posture, although it may produce a reduced lumbar lordosis in standing and greater thoracic and lumbar bending in maximal forward flexion The discipline of paddling (kayak or canoe) does not influence sagittal spinal curvatures in young male paddlers. The position and movements of paddling do not appear to have any influence in the hamstring muscle extensibility because the paddlers have similar extensibility than the non-athlete subjects.
Revisiting the influence of hip and knee angles on quadriceps excitation measured by surface electromyography : original research articleSource: International SportMed Journal 11, pp 313 –323 (2010)More Less
Background: The quadriceps muscle group includes one biarticular (crosses the hip and the knee) and three monoarticular (crosses the knee only) muscles. The influence of hip and knee angles on quadriceps muscles excitation remains inconclusive in the literature. Research question: To re-examine the excitation of the biarticular and monoarticular quadriceps muscles during maximum voluntary isometric contractions at different hip and knee angles. Type of study: Cross-sectional experimental study. Methods: Ten recreationally active subjects (5 males, 5 females) performed maximum voluntary isometric contraction of knee extensors at six knee angles (90°, 100°, 110°, 120°, 130° and 140°) on an isokinetic dynamometer. The protocol was repeated at three hip positions: sitting, inclined and supine. During the test, surface electromyography was employed to record muscle activity of the rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM). Repeated measures ANOVA (hip x knee) was used to determine the effect of hip and knee angles on peak torque and muscle excitation. Results: A significant hip by knee interaction was found for RF (P = 0.013). As the knee angle increased, VL and VM excitation decreased (P < 0.001). Higher excitation was observed in the sitting position, followed by inclined and then the supine position for both VL (P = 0.004) and VM (P = 0.046). Conclusions: As expected, changes in knee angle influence the excitation of all surface quadriceps muscles. However, changes in hip angle, though only alter the biarticular muscle length, influence both biarticular and monoarticular muscle excitation. The large discrepancy among studies warrants further attention.