Table 5.

Examples of screening and monitoring options for risk of future calf muscle strain injuries

Domain	Outcome of interest	Tests and example benchmarks
Non-modifiable intrinsic factors	Injury history	History of CMSI; other injury history or current sub-clinical state: foot (1st MTPJ, plantar fascia, bone stress, fractures), ankle (sprains, fractures, Achilles), knee, lumbar spine, other muscle strains (hamstring, quadriceps, adductor), including history of recurrent injuries; ethnicity
	Chronological age	Age: years
	Body mass index	kg m2
Range of motion and tissue extensibility	Weight bearing dorsiflexion Posterior extensibility	Knee-to-wall lunge test: Range of motion (cm); asymmetry ≤ 10% Standing flexion, or sit-and-reach test
Isolated calf strength	Foundation strength-endurance	Single leg calf raise test: capacity (repetitions to fatigue ≥ 30), asymmetry ≤ 10%, movement quality/ coordination. Metronome paced (30 beats/ minute); performed from the floor* to fatigue + / − a cut-off
	Loaded strength	Smith and/or seated calf machines: ideal relative strength benchmarks ≥ 1.0xBW for knee extended (0°) and ≥ 1.5xBW for knee flexed (90°); asymmetries ≤ 10%. Various RM regimes pending sport (1RM-8RM)
Power capacities and function during dynamic activities	Vertical	Single leg drop jump or single leg CMJ: total height (cm), reactive strength index, early RFD, late RFD, eccentric impulse; asymmetries ≤ 10%; movement quality/ coordination
	Horizontal	Forward hop test: distance (m); asymmetry ≤ 10%; movement quality/ coordination. Measured using a single or multiple hops ≥ 3, or as single-leg bound in high-level athletes; 20 m prowler sprint test
Exposure history	Recent	Details of any interruptions to usual exposure; details of recent program: velocities, volumes, exposure to specialised activities of the sport (multi-axial, acceleration, deceleration, metabolic), GPS data
	Medium–long term	Workload data; training age (i.e. number of years playing sport, completing on-field and off-field strength and conditioning activities/ exercises); GPS data; preseason completeness > 80%
	Loading conditions	Running surfaces; footwear; orthotics

CMSI calf muscle strain injuries; MTPJ metatarsophalangeal joint; RM repetition maximum; RFD rate of force development

^*Note: testing single leg calf raise capacity from the floor (rather than a step) was perceived to limit the potentially significant impact of individual variation in ankle dorsiflexion range of motion