. Differential displacement of the human soleus and medial gastrocnemius aponeuroses during isometric plantar flexor contractions in vivo. J Appl Physiol 97: 1908 -1914, 2004. First published June 25, 2004 doi:10.1152/ japplphysiol.00084.2004.-The human triceps surae muscle-tendon complex is a unique structure with three separate muscle compartments that merge via their aponeuroses into the Achilles tendon. The mechanical function and properties of these structures during muscular contraction are not well understood. The purpose of the study was to investigate the extent to which differential displacement occurs between the aponeuroses of the medial gastrocnemius (MG) and soleus (Sol) muscles during plantar flexion. Eight subjects (mean Ϯ SD; age 30 Ϯ 7 yr, body mass 76.8 Ϯ 5.5 kg, height 1.83 Ϯ 0.06 m) performed maximal isometric ramp contractions with the plantar flexor muscles. The experiment was performed in two positions: position 1, in which the knee joint was maximally extended, and position 2, in which the knee joint was maximally flexed (125°). Plantarflexion moment was assessed with a strain gauge load cell, and the corresponding displacement of the MG and Sol aponeuroses was measured by ultrasonography. Differential shear displacement of the aponeurosis was quantified by subtracting displacement of Sol from that of MG. Maximal plantar flexion moment was 36% greater in position 1 than in position 2 (132 Ϯ 20 vs. 97 Ϯ 11 N ⅐ m). In position 1, the displacement of the MG aponeurosis at maximal force exceeded that of the Sol (12.6 Ϯ 1.7 vs. 8.9 Ϯ 1.5 mm), whereas in position 2 displacement of the Sol was greater than displacement of the MG (9.6 Ϯ 1.0 vs. 7.9 Ϯ 1.2 mm). The amount and "direction" of shear between the aponeuroses differed significantly between the two positions across the entire range of contraction, indicating that the Achilles tendon may be exposed to intratendinous shear and stress gradients during human locomotion. triceps surae; Achilles tendon; ultrasound; connective tissue mechanical properties; tendon shear strain; intratendinous stress THE HUMAN TRICEPS SURAE muscle-tendon structure is intricate in constitution and function, with three separate muscle compartments that merge via their aponeuroses into a common tendon to ultimately insert on the calcaneus. The combined forces generated by the triceps surae muscles during locomotion are transmitted to the Achilles tendon and may reach 1,400 -2,600 N during walking and 3, 100 -5,330 N during running (13, 15, 34). It has been suggested that these large forces imposed on the tendon contribute to various loading-related pathologies such as tendinopathy (19), although the exact etiology remains largely intangible. Consequently, a more detailed understanding of the intrinsic contraction properties of the multipart triceps surae structure may contribute to the development of future treatment paradigms and/or prophylactic intervention models.Information on the mechanical properties and function of the aponeurosis and tendon have tradition...

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In studies of physical performance comprising muscle strength and power, a vertical jump is a test method that frequently is used. It is important to have access to accurate measuring tools providing data with high reproducibility. Studies have shown that body composition also may play an important part in physical performance. The purpose of this study was to determine test-retest reliability for 3 different kinds of vertical jumps and to correlate jump height with body composition. Thirty-four normally trained subjects (women n = 17) between 18 and 25 years participated. Test-retest, on 3 kinds of vertical jumps, was performed with a median of 7 days between jumps. Methods used were a countermovement jump (CMJ) on a contact mat, with and without arm swing, and an Abalakow jump (AJ) using measuring tape, with arm swing. Body composition was assessed with the use of bioelectric impedance analysis. The results showed that high intraclass correlation coefficients (ICCs) were observed between testing occasions for all 3 vertical jumps (ICC between 0.48 and 0.88). The AJ in women presented the lowest ICC. Also the correlation between CMJ and AJ was high (rs = 0.88). Moderate-to-high correlations could be shown between body composition and CMJ in women (rs = -0.57-0.76). In conclusion, very high test-retest reliability for CMJ on a contact mat was found. For the AJ using a measuring tape, ICC were overall high, but a moderate nonsignificant ICC were found in women, indicating poor reproducibility. The data from the CMJ and AJ may be compared if approximately 25% of the AJ value is subtracted. In practice, this means that vertical jump tests have high reproducibility and can be used as measures of power development.

BackgroundPhysical activity (PA) and health-related quality of life (HRQoL) are important factors for optimal health in the elderly. Studying the association between PA and HRQoL is becoming more essential as the number of elderly people increases worldwide. This study assesses the association between PA and HRQoL among community dwelling elderly above 60 years old.MethodsThe study included 115 women and 61 men (mean age: 68.15 ± 6.74 years) recruited from the community and from public centers for the elderly. Data were collected using a background characteristics questionnaire (BCQ), a physical activity socio-cultural adapted questionnaire (PA-SCAQ), and the EuroQuol-5Dimensions-5Levels (EQ-5D-5L) questionnaire. Between groups, comparisons were based on the PA-SCAQ by dividing the participants into three PA groups: low (n = 74), moderate (n = 85), and high (n = 17). Kruskal-Wallis tests were performed on the ordinal variables of the three PA groups to determine differences between the groups according to categorical variables such as gender, body mass index (BMI), and the prevalence of comorbid conditions. Mann-Whitney U tests were performed on the ordinal variables of the EuroQuol-5Dimensions (EQ-5D), and the independent sample t-test was performed on the EQ visual analogue scale (EQ-VAS). Spearman’s rank correlation coefficient was used to examine the correlation between the EQ-5D and level of PA.ResultsValues in all dimensions of HRQoL were significantly higher (P < 0.05) in the moderate and high PA groups compared with the low PA group. Significant correlations were recorded between the five dimensions of HRQoL and the level of PA (P < 0.001). The low PA group showed higher prevalence of hypertension (64%, P < 0.001) and diabetes (50%, P < 0.001).ConclusionThere were strong associations between higher levels of PA and all dimensions of HRQoL. Therefore, adopting a PA lifestyle may contribute to better HRQoL among community dwelling elderly above 60 years old.

The purpose of this study was to examine the prevalence of injury and the extent of preventive actions in elite Swedish volleyball players. Injuries to players in the elite male and female Swedish division, during the 2002-2003 season, were registered by using a questionnaire. Of the 158 volleyball players (70% response rate), a total of 82 players (52%) reported 121 injuries, during a total exposure time of 24 632 h, representing an overall incidence of 0.77 injuries per player. The majority of the injuries were located in the ankle (23%), followed by the knee (18%) and the back (15%). Most injuries (62%) were classified as being of minor severity. Most injuries occurred during training (47%), and 41% of the injuries had a gradual onset. Fifty-four percent of the injuries that could be related to a specific court situation occurred during blocking, and 30% during spiking. Most players (96%) participated in injury prevention training of some kind, generally performed without supervision (58%). Although most players took part in some kind of preventive action, one out of two players incurred an injury during the season, which indicates that the risk of suffering an injury in elite volleyball is relatively high.