Background: Cycling is considered to be a highly beneficial sport for significantly enhancing cardiovascular fitness in individuals, yet studies show little or no corresponding improvements in bone mass. Methods: A scientific literature search on studies discussing bone mass and bone metabolism in cyclists was performed to collect all relevant published material up to April 2012. Descriptive, cross-sectional, longitudinal and interventional studies were all reviewed. Inclusion criteria were met by 31 studies. Results: Heterogeneous studies in terms of gender, age, data source, group of comparison, cycling level or modality practiced among others factors showed minor but important differences in results. Despite some controversial results, it has been observed that adult road cyclists participating in regular training have low bone mineral density in key regions (for example, lumbar spine). Conversely, other types of cycling (such as mountain biking), or combination with other sports could reduce this unsafe effect. These results cannot yet be explained by differences in dietary patterns or endocrine factors. Conclusions: From our comprehensive survey of the current available literature it can be concluded that road cycling does not appear to confer any significant osteogenic benefit. The cause of this may be related to spending long hours in a weight-supported position on the bike in combination with the necessary enforced recovery time that involves a large amount of time sitting or lying supine, especially at the competitive level.

Objective: To review the characteristics of the injuries among CrossFit® practitioners, including prevalence and incidence, nature, location, and risk factors. Methods: PubMed/MEDLINE, EMBASE, Web of Science, Scopus, and SPORTDiscus databases were searched from inception through August 2020, and English-language articles reporting on CrossFit®-related injuries were included. Data including sample (sex, age, and demographics) and injuries’ characteristics (prevalence, incidence rate, nature, location, percentage of injuries requiring surgery and risk factors) were extracted. Results: Overall, twenty-five studies involving a total of 12,079 CrossFit® practitioners met the inclusion criteria. The mean prevalence of injuries among the included studies was 35.3%, with an incidence rate varying between 0.2 and 18.9 per 1000 hours of training. The most injured areas were shoulder (26%), spine (24%), and knee (18%). Among the studies that reported the injuries requiring surgery, the mean percentage was 8.7%. Regarding the risk factors associated with injuries, older age, male sex, a greater body mass index, the existence of previous injuries, the lack of coach supervision, the experience on CrossFit® and the participation in competitions were reported by the studies. Conclusions: CrossFit® training has an injury incidence rate similar to weightlifting and powerlifting. Findings from the studies suggest that the most affected areas are shoulder, spine, and knee. The limited quality of the studies prevents us from drawing solid conclusions about injury risk factors.

The effects of a training program consisting of weight lifting combined with plyometric exercises on kicking performance, myosin heavy-chain composition (vastus lateralis), physical fitness, and body composition (using dual-energy X-ray absorptiometry (DXA)) was examined in 37 male physical education students divided randomly into a training group (TG: 16 subjects) and a control group (CG: 21 subjects). The TG followed 6 weeks of combined weight lifting and plyometric exercises. In all subjects, tests were performed to measure their maximal angular speed of the knee during instep kicks on a stationary ball. Additional tests for muscle power (vertical jump), running speed (30 m running test), anaerobic capacity (Wingate and 300 m running tests), and aerobic power (20 m shuttle run tests) were also performed. Training resulted in muscle hypertrophy (+4.3%), increased peak angular velocity of the knee during kicking (+13.6%), increased percentage of myosin heavy-chain (MHC) type IIa (+8.4%), increased 1 repetition maximum (1 RM) of inclined leg press (ILP) (+61.4%), leg extension (LE) (+20.2%), leg curl (+15.9%), and half squat (HQ) (+45.1%), and enhanced performance in vertical jump (all p ≤ 0.05). In contrast, MHC type I was reduced (–5.2%, p ≤ 0.05) after training. In the control group, these variables remained unchanged. In conclusion, 6 weeks of strength training combining weight lifting and plyometric exercises results in significant improvement of kicking performance, as well as other physical capacities related to success in football (soccer).