Clinical Testing of Calf Strength and Hopping

Peter sets out standing calf raises with a slow two to three second tempo, full range, an upright trunk and push-off over the big toe, then compares repetitions side to side and against population norms: upwards of 30 for people in their 20s and 30s, and under 20 or even 15 in their 70s and 80s. A seated bent-knee calf raise in a Smith machine, tested as an eight-repetition maximum with a metronome and good knee padding, gives a controlled strength measure; runners without Achilles pain reached about 1.5 times body weight, and those with pain much less. Hopping follows the spring mass model, with a preferred frequency of about 2 Hz. An efficient hop has short contact time and long flight time, while a sluggish hop may point to pain, calf weakness or poor power. The My Jump app can estimate jump height and vertical stiffness, and a clinic force plate adds force, contact and flight times across hop types.