Rapid force production declines as a consequence of ageing. Given the functional relevance of rapid force production, exercise interventions in older adults should aim at improving the capacity to produce force rapidly. To improve this capacity, exercises should be performed with the intention to develop high speeds, as supported by previous work. Human locomotion fundamentally consists of multi-joint movements and rapidly coupled eccentric-concentric muscle actions, known as stretch-shortening cycle (SSC) activities or plyometrics. Plyometrics might therefore be used to optimize power production. However, there is limited research on the feasibility of plyometrics in older adults and its potential effects on rapid force production and functional capacity. This study will test the feasibility of a 12-week plyometric exercise intervention in older men and compare its effects on rapid force production to a traditional resistance exercise or walking intervention.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
42
12-week progressive training intervention
Department of Movement Sciences
Leuven, Belgium
Rapid force production
Subjects perform a test protocol on a sledge apparatus, consisting of explosive isometric voluntary contractions for the leg-extensor muscles of the right leg. The inclination of the sledge is 20° to horizontal. The seat of the sledge is inclined backwards (130°). The knee joint angle is set at 90° and the hip angle at 70°. The point of force application is aligned with the head of the fifth metatarsal. Subjects are instructed to kick as fast and as hard as possible and maintain their maximum force for approximately 3s. The rate of force development (N/s) is defined as the linear slope of the force-time curve and is measured from the onset of movement till 100 ms.
Time frame: Change from baseline in rapid force production at 12 weeks
Jumping height in squat jump
Subjects perform a test protocol on a sledge apparatus, consisting of squat jumps (SJ), countermovement jumps (CMJ), and drop jumps (DJ). The inclination of the sledge is 20° to horizontal. The seat of the sledge is inclined backwards (130°). A force platform is built in perpendicular to the jumping direction. A speed sensor is attached to the seat of the sledge, which is used to assess the transition point between braking and push-off phases and to calculate jumping height (in cm).
Time frame: Change from baseline in jumping height at 12 weeks
Jumping height in countermovement jump
Subjects perform a test protocol on a sledge apparatus, consisting of squat jumps (SJ), countermovement jumps (CMJ), and drop jumps (DJ). The inclination of the sledge is 20° to horizontal. The seat of the sledge is inclined backwards (130°). A force platform is built in perpendicular to the jumping direction. A speed sensor is attached to the seat of the sledge, which is used to assess the transition point between braking and push-off phases and to calculate jumping height (in cm).
Time frame: Change from baseline in jumping height at 12 weeks
Jumping height in drop jump
Subjects perform a test protocol on a sledge apparatus, consisting of squat jumps (SJ), countermovement jumps (CMJ), and drop jumps (DJ). The inclination of the sledge is 20° to horizontal. The seat of the sledge is inclined backwards (130°). A force platform is built in perpendicular to the jumping direction. A speed sensor is attached to the seat of the sledge, which is used to assess the transition point between braking and push-off phases and to calculate jumping height (in cm).
Time frame: Change from baseline in jumping height at 12 weeks
Leg press one-repetition maximum
Leg press one-repetition maximum is defined as the maximum weight (in kg) that the subject can push on a leg press device (Signature Series Leg press Life Fitness).
Time frame: Change from baseline in leg press 1-RM at 12 weeks
Maximal isometric strength
Maximal strength (Nm) is measured by means of unilateral isometric knee-extensor tests on a Biodex dynamometer.
Time frame: Change from baseline in maximal isometric strength at 12 weeks
Maximal isokinetic strength
Maximal strength (Nm) is measured by means of unilateral isokinetic knee-extensor tests on a Biodex dynamometer.
Time frame: Change from baseline in maximal isokinetic strength at 12 weeks
Stair Climbing performance
Stair ascent duration (in s), the time needed to ascent a flight of stairs.
Time frame: Change from baseline in Stair Climbing performance at 12 weeks
Gait speed
The average speed to walk 10m as fast as possible (in m/s).
Time frame: Change from baseline in gait speed at 12 weeks
5 repetition sit-to-stand test
The time needed to perform 5 sit-to-stand transitions (in s).
Time frame: Change from baseline in sit-to-stand duration at 12 weeks
6 minute walk distance
The walk distance (in m) covered in 6 min.
Time frame: Change from baseline in 6min walk distance at 12 weeks
Balance
Overall balance performance is assessed using the total length of the sway path divided by duration of the measurement (mm/s) in a 30s balance test on a balance board.
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Time frame: Change from baseline in balance at 12 weeks