Evaluation of an innovative critical power model in intermittent vertical jump.

The aim of this study was to test if the critical power model can be used to determine the critical rest interval (CRI) between vertical jumps. Ten males performed intermittent countermovement jumps on a force platform with different resting periods (4.1+/-0.3 s, 5.0+/-0.4 s, 5.9+/-0.6 s). Jump trials were interrupted when participants could no longer maintain 95% of their maximal jump height. After interruption, number of jumps, total exercise duration and total external work were computed. Time to exhaustion (s) and total external work (J) were used to solve the equation Work=a+b x time. The CRI (corresponding to the shortest resting interval that allowed jump height to be maintained for a long time without fatigue) was determined dividing the average external work needed to jump at a fixed height (J) by b parameter (J/s). In the final session, participants jumped at their calculated CRI. A high coefficient of determination (0.995+/-0.007) and the CRI (7.5+/-1.6 s) were obtained. In addition, the longer the resting period, the greater the number of jumps (44+/-13, 71+/-28, 105+/-30, 169+/-53 jumps; p<0.0001), time to exhaustion (179+/-50, 351+/-120, 610+/-141, 1,282+/-417s; p<0.0001) and total external work (28.0+/-8.3, 45.0+/-16.6, 67.6+/-17.8, 111.9+/-34.6kJ; p<0.0001). Therefore, the critical power model may be an alternative approach to determine the CRI during intermittent vertical jumps.

Grip force control during simple manipulation tasks in non-neuropathic diabetic individuals.

OBJECTIVE: To assess hand function and grip force (GF) control in non-neuropathic diabetic individuals using traditional hand function tests and instrumented handles that provide information about the underlying neural mechanisms controlling simple manipulation tasks. METHODS: Twelve diabetic individuals (31-60 years-old) without neuropathy and 12 controls performed traditional functional tests (i.e., nine hole peg test, Jebsen-Taylor test, and maximum grip strength test) and were tested for GF control in two situations: holding a free moving instrumented handle and isometrically pulling fixed handles. Task performance in the tests and safety margin (SM - percentage of GF above the minimum needed to hold the handle) were the main dependent variables assessed. RESULTS: There was no difference between diabetics and controls in any functional test and in SM in isometric pulling task. However, diabetics presented around twice lower SM than controls in the free holding task. CONCLUSIONS: Diabetics showed no impairment in functional manipulation tasks. However, they presented a lower SM than healthy controls. SIGNIFICANCE: This lower SM suggests that diabetics may present sensory impairment that could put them at risk of losing objects during its manipulation. Also, it suggests that the applied experimental procedure is sensitive to detect mild sensory impairment in diabetics.