A dynamometer for evaluation of dynamic muscle work.
The validation of a new dynamometer for evaluation of dynamic muscle work is presented. The device was based on a precise measurement of load displacements of any machine using gravitational loads as external resistance. It allowed, through a sensor consisting of an infrared photo interrupter, the calculation of velocity, force and power during concentric, eccentric and stretch-shortening cycle activity. To validate the dynamometer 33 male and female track and field athletes (12 throwers and 21 jumpers) participated in the study. The throwers (4 women and 8 men) were asked to perform half-squat exercises on a slide machine with a load of 100% of the subject's body mass. The day-to-day reproducibility of half-squat exercises gave a correlation coefficient of r = 0.88, 0.97 and 0.95 for average push-off force (AF), average push-off velocity (AV), and average push-off power (AP) respectively. Comparison of half-squat measurements was performed against jumping and running test evaluation by the jumpers (7 women and 14 men). The interrelationships among the different variables studied demonstrated a strong correlation between AF, AV and AP and sprinting and jumping parameters (r = 0.53-0.97; P < 0.05-0.001). Using values of AF, AV and AP developed in half-squat exercises executed with different loads, ranging from 35% to 210% of the subject's body mass, it was also possible to establish the force-velocity and power-velocity relationships for both male and female jumpers. In any individual case, the maximal error due to the measurement system was calculated to be less than 0.3%, 0.9% and 1.2% for AF, AV, and AP respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Bosco
C
C
Department of Physical Medicine and Rehabilitation, Faculty of Medicine and Surgery, University of Roma Tor Vergata, Rome, Italy.
Belli
A
A
Astrua
M
M
Tihanyi
J
J
Pozzo
R
R
Kellis
S
S
Tsarpela
O
O
Foti
C
C
Manno
R
R
Tranquilli
C
C
D000328:Adult; D002138:Calibration; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D009132:Muscles / Q000502:physiology*; D010806:Physical Education and Training; D005082:Physical Exertion / Q000502:physiology*; D010827:Physiology / Q000295:instrumentation*; D012420:Running; D012727:Sex Characteristics