Plyometric Exercise to Improve Rapid Force Production in Older Men

Study Overview
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Brief Summary
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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.

Official Title
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Plyometric Exercise to Improve Rapid Force Production in Older Men: a Pilot Intervention

Conditions
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Exercise Training

Intervention / Treatment
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* Other: Exercise intervention


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - Exclusion Criteria: No systematic engagement in (resistance) exercise in the 12-months prior to participation Cardiovascular disease Neurological disorders Cognitive malfunctioning Severe knee or hip problems

Ages Eligible for Study
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Minimum Age: 65 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Plyometric exercise<br>12-week progressive exercise program, consisting of plyometric exercises such as countermovement jump, forward and sideways step-up. | Other: Exercise intervention<br>* 12-week progressive training intervention<br>|
| Active Comparator: Resistance exercise<br>12-week resistance exercise program for the leg muscles (2-4 sets of 8-15 repetitions at 8-15RM, leg press, leg extension, calve extension). | Other: Exercise intervention<br>* 12-week progressive training intervention<br>|
| Active Comparator: Walking<br>12-week progressive walking program. | Other: Exercise intervention<br>* 12-week progressive training intervention<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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. | 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). | 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). | 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). | Change from baseline in jumping height at 12 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| 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). | 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. | 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. | 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. | 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). | 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). | Change from baseline in sit-to-stand duration at 12 weeks | 
| 6 minute walk distance | The walk distance (in m) covered in 6 min. | 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. | Change from baseline in balance at 12 weeks |