A quick refresher. Force (mass x acceleration) capability in your athletes can be developed by emphasising mass, athletes overcoming large loads on bars. A consequence of such loading is that movement velocities and accelerations are slow/small (see picture). Conversely you can develop force capability in athletes by emphasising acceleration and therefore moving light loads quickly. Or you can mix it up and use both methods.

 Have a look at these stats and see if you think light loading can provide serious overload for your athletes. Martin and Cavangh(1990) had subjects run (not sprint) with 250 or 500 grams attached to the thigh or the foot, and reported these main findings.

• Foot loading = ~15-17% é in moments and power at the hip, knee and ankle.
• Thigh loading only affected the hip moments and to lesser magnitude.
• Foot loading é9.1% (0.25 kg) and 19.7% (0.5 kg) work-energy.
• Limb kinematics (technique) minimally affected.

Move a light load quickly and you’re developing high velocity force capability. Place the load further from the axis of rotation e.g. (hip – ankle distance) and then you have seriously upped the muscular demands. It’s just physics.

Martin and Cavanagh (1990) Segmentinteractions within the swing leg… J. Biomechanics, 23(6), 529-536.

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