Six sessions of 30-second sprints doubled cycling endurance in two weeks. What SIT does to VO2max, muscle and body fat - with the numbers from a 55-study analysis - and why the rest interval is not a detail.

Alternating heavy and light days is the oldest trick for getting past a stall. The trials and a 35-study meta-analysis say it works - for maximal strength, in trained lifters, with a moderate effect - and does nothing extra for muscle size. Here is how to structure and log it.

Injury is rarely one thing. It is a susceptible athlete meeting an exposure at the wrong moment. Here is what the evidence says about which intrinsic and extrinsic factors matter - and which interventions cut injury risk by around a third to 40%.

Bosu balls and wobble discs do improve balance and build strength in untrained people. They do not increase core activation over a stable floor at equal loads, and in trained athletes they blunt sprint and jump gains. Here is where instability belongs in a programme.

The 150-300 minute weekly target is a dose-response curve, not a cliff. Across 30 million people, 150 minutes of moderate activity is associated with a 31% lower risk of death, and half that dose still delivers a large share of the benefit. Here are the guidelines and the numbers behind them.

Water lowers impact and heart-rate ceilings, and in 32 trials aquatic exercise beat doing nothing on pain and function and edged land-based exercise on pain alone. Here is what training in water does and does not do, and which people gain most from it.

Across 45 studies and 33,000 adolescents, heavier social media use is linked to more body image concern and disordered-eating symptoms, with the strongest effects on Instagram and in girls. Exposure to idealised images raises dissatisfaction in minutes; body-diverse content lowers it. Here is the evidence and what coaches and parents can do.

Pooling 43 studies, adding endurance work to lifting leaves hypertrophy and maximal strength untouched and dents explosive strength - mostly when both are done in one session. Sprint intervals alongside lifting even raised VO2max with no strength cost. Here is how to programme both.

Across 15 trials, combined aerobic and resistance training shed about two kilograms more weight and fat than lifting alone, while lifting preserved over a kilogram more lean mass than cardio. And moderate exercise cuts abdominal fat even when weight does not fall. Here is the evidence.