Although push-ups and sit-ups are among the most commonly used body-weight exercises to improve and assess strength and fitness, there is a lack of reproducible test protocols in the scientific literature. The aim of this study was to evaluate the test–retest reliability of sit-ups and push-ups and to determine performance differences in muscular endurance (maximal number of repetitions) and power (timed, maximal number of repetitions in 30 s) in young women and men. Thirty-eight women and 25 men, 18–35 years of age, participated in the study. Thirteen women participants performed two test sessions of each test using a test–retest design. A high reliability was noted for both the sit-up and the push-ups tests (intraclass correlation values ranged from 0.92 to 0.95). There were no significant differences between the men and the women in the mean number of sit-ups (42 and 41 repetitions respectively for endurance and 16 and 14 repetitions respectively for power), whereas the men performed significantly more push-ups than the women (39 and 17 repetitions respectively for endurance and 29 and 13 repetitions respectively for power). In conclusion, sit-ups and push-ups are tests with high reliability, which are easy to perform and may therefore be recommended for clinical use to evaluate muscular endurance and power in young men and women. Moreover, the fact that men performed twice as many push-ups as women indicates that, when designing training programme for women, attention should be turned towards strengthening exercises of the upper body.

Background: The role of lower extremity (LE) muscle strength for predicting traumatic knee injury in youth athletes is largely unknown. Aims: The aim was to investigate the influence of LE muscle strength on traumatic knee injury in youth female and male athletes. Methods: 225 athletes (40% females) from sport senior high schools in Sweden were included in this case–control study. The athletes recorded any traumatic knee injury that had occurred during their high-school period in a web-based injury form. A one repetition maximum (1RM) barbell squat test was used to measure LE muscle strength. The 1RM was dichotomised to analyse ‘weak’ versus ‘strong’ athletes according to the median (weak_median vs strong_median). Results: 63 traumatic knee injuries, including 18 ACL injuries, were registered. The majority of injured female athletes were in the weak group compared with the strong group (p=0.0001). The odds of sustaining a traumatic knee injury and an ACL injury was 9.5 times higher and 7 times higher, respectively, in the weak_median group compared with the strong_median group in females (p ≤0.011). A relative 1RM squat ≤1.05 kg (105% of bodyweight) was established as the best cut-off value to distinguish high versus low risk of injury in female athletes. No strength–injury relationships were observed for the male athletes (p ≥0.348). Conclusions: Weaker LE muscle strength predicted traumatic knee injury in youth female athletes, but not in males. This suggests that LE muscle strength should be included in injury screening in youth female athletes.

The aim of this study was to evaluate the effects of a 26-week individualized and supervised strength and injury prevention program on performance enhancement in young female volleyball players who completed resistance training with either a supervised and individualized training program (experimental group, n=10) or an unsupervised non-individualized training program (control group, n=17). Exposure and injury data were collected during the 2006–2007 season (baseline season) and the 26-week program was conducted during the 2007–2008 season (intervention season). All players were tested for physical performance. At post-test, the players in the experimental group had improved significantly more than the players in the control group for squat (p<0.0001), bench press (p=0.048), push-ups (p=0.02) and sit-ups (p<0.0001) but not for the vertical jump test. Thirty-five percent (6/17) of the players from the control group and 80% (8/10) of the players in the experimental group completed the resistance training with compliance of no less than 50%. The present study shows the importance of individualization and supervision for resistance training in young female athletes when it comes to compliance, strength gains and performance.

Background: Studies investigating postural orientation in uninjured youth athletes are scarce. Understanding how postural orientation during functional performance tests change with age in uninjured athletes has the potential to enhance awareness of changes in performance after injury and to set realistic goals for injured athletes. Thus, the aim of this study was to explore postural orientation during functional tasks at early adolescence, and changes in postural orientation from early to middle adolescence and relate this to sex, type of sport and right leg lean body mass (RLLBM). Methods: In this cohort study 144 (38% female) youth athletes (mean age 13.5 years, SD 0.3) were included at baseline and 86 of these at follow up 2 years later. Four functional performance tests were visually evaluated for Postural Orientation Errors (POEs) with an ordinal scale, ranging from 0 (good) to 2 (poor), yielding a maximum total POE score of 51, and RLLBM by dual energy X-ray absorptiometry. Results: Improvements were observed in the total POE score from baseline to follow-up, median difference − 10 and − 7 (p < 0.001) for female and male athletes, respectively. At follow-up, female athletes had lower total POE score (median 18) than males (median 24) (p = 0.01). There were no differences in POE scores between sports type (team, individual, aesthetic) (p = 0.20–0.98) and no relationship between total POE score and RLLBM (r_s = 0.09, p = 0.42). Conclusions: POEs appear to be quite common in young athletic population, but improvements are achieved over time. At mid-adolescence, female athletes seem to have less POEs than males. Neither sport type nor RLLBM seem to influence postural orientation.

Although bench press and squat are two of the most frequently performed strength training exercises today, and are used for physical performance assessment in many sports test batteries as well as in physical therapy, studies presenting inter-rater reliability for these tests in young women appear to be lacking in the literature. The aim of this study was to evaluate inter-rater reliability regarding the One Repetition Maximum (1 RM) in bench press and squats in young healthy women. Forty-one women, aged 21–30 years, participated in the present study. The subjects performed 1 RM bench press (n = 21) or 1 RM squat (n = 20) on two different occasions with an interval of 5–9 days using an inter-rater test-retest design. High reliability was noted for both the 1 RM bench press test (ICC_2,1 = 0.98) and the 1 RM squat test (ICC_2,1 = 0.85), with an SEM of 4% and 11%, respectively. The paired analysis revealed statistically significant difference in 1 RM squat performance between the two test sessions (p = 0.005). No statistically significant difference was found in 1 RM bench press performance between the two testing sessions. While the 1RM bench press showed excellent inter-rater reliability and could be strongly suggested as a measurement of muscle strength, the squat using free weights, as in the present study, could be questioned.