Male powerlifters, especially the strongest, had less shoulder and some hip range of motion than controls, with better hamstring flexibility. Female national-level powerlifters did not have reduced range of motion compared with recreationally trained women.

In small crossover studies, dynamic stretching raised leg-extension power and jump power, ballistic stretching did not change jump measures, and 30-second dynamic protocols improved countermovement jumps (no jump gain was reported for 75-second bouts), while every protocol improved range of motion. None varied the amplitude of the movement.

In a six-week randomised trial, balance training done after interval training produced smaller adaptations than training it fresh, even when tested fatigued. Separately, muscle fatigue impaired motor-skill learning on later practice days.

Two 10-minute stretches a day during two weeks of ankle immobilisation reduced the loss of calf peak torque and ankle mobility, and one to two hours of daily stretching for six weeks increased calf strength in active adults.

In a randomised trial of 5,201 female navy recruits, calcium and vitamin D lowered stress fracture incidence during basic training. In 756 Finnish recruits, below-median vitamin D at entry was linked to higher odds of stress fracture (OR 3.6). Evidence covers bone stress injury, not injuries in general.

Powerlifters with low back pain scored no differently on a seven-test lumbopelvic movement control battery than those without. Injuries are common, with the lumbopelvic region among the most affected areas, but most lifters keep training.

In a Norwegian cohort of about 30,000 pain-free adults, more hours of weekly exercise were linked to lower risk of chronic low-back and neck or shoulder pain at follow-up in 1995–1997. In adults with chronic pain, an overview of 21 Cochrane reviews found most reported adverse events were increased soreness or muscle pain that reportedly subsided after a few weeks.

Return-to-play screening of professional and college athletes in 2020 found cardiac involvement after COVID-19 to be uncommon, with symptoms and abnormal basic tests predicting it. A 2021 systematic review found reported rates varied widely with study quality.

A meta-analysis of 21 studies found pre-exercise foam rolling improved flexibility by 4.0% with negligible effects on strength and jump. Two trials found range of motion rose after rolling with no loss of force, activation or power.

Across 55 trials, loaded resistance training improved range of motion (ES 0.73) and matched stretching; combined lifting and stretching did no better than stretching alone. Bodyweight-only training did not help.

By incidence, powerlifting is a low-risk sport: about 1 to 4 injuries per 1,000 training hours. By prevalence, 70% of sub-elite lifters are currently in pain that changes their training. Both are true.

Static stretching cut strength by 5.4% on average, but holds under 30 to 45 seconds had little or no effect, and adding dynamic activity afterwards makes the effect inconsequential.

Pain neuroscience education combined with physiotherapy improved short-term pain and disability modestly in chronic low back pain; alone, its effect may be zero, and no lasting benefit was shown.

In a 45-person randomised trial, 2 minutes on a vibrating roller raised pressure pain threshold more than a normal roller (P = .03) but improved knee range of motion by a similar amount (P = .31).

Pooled controlled studies put cross-education at 7.8% of initial strength (95% CI 4.1–11.6), about 35% of the trained limb's gain. Inclusive pooling suggests ~18% in healthy adults and 29% in neuromuscular patients. The mechanism is neural.

Stretching before or after exercise cut next-day soreness by about half a point to one point out of 100 and did not restore strength faster than resting (ES −0.08). Stretch for range of motion, not recovery.

Light loads under a cuff build strength at close to the heavy-load rate in healthy adults and at a moderate rate in rehabilitation. When heavy loading is off the table, it is the best-supported substitute.

Long-term steroid users among experienced bodybuilders had a markedly higher lifetime risk of tendon rupture, mostly upper body, and their tendons were stiffer and reached higher maximal stress.

Across 27 studies, tendon stiffness rose by a pooled 0.70 SD, mostly through stiffer material rather than a thicker tendon. Loading intensity decided the response; contraction type did not.

In postmenopausal women, 5 g/day of collagen peptides raised spine and hip bone density slightly over a year; in athletes, 10 g/day modestly eased joint pain. Gelatin was not tested.