Training specificity has always been a key component of athletic preparation and jump squats are VERY specific. In this article we look at optimal training loads for the development of power when using jump squats.
In 2002 McBride et al conducted a study that investigated power and speed development utilizing different training loads. The study split the subjects (trained athletes) into a number of groups. These were a heavy jump squat training group, a light jump squat training group and a non-training control group. Differences in the three groups were examined after an 8-week training period.
The heavy training group underwent the following training protocol: Training was carried out on a braked Smith machine configured to minimize the impact on the landing phase of the exercises. A linear position transducer was used to determine bar displacement although it is unclear if this information was made available to the subject during the training (this is significant as in the last article we looked at the training effect was increased by 20% when the subjects were given this information during their training sets). After a warm up on a stationary bike they performed 2 warm up sets of 6 jump squats one with the bar alone and the next with 50% of their 1RM. This was followed by 4 sets of 6 jump squats at 80% of their 1RM squat weight.
The light training group underwent the following training protocol: As with the heavy training group all training was carried out on a braked smith machine with a linear position transducer attached to the bar. They performed 1 warm up set of 6 repetitions with the bar alone. They then performed 5 sets of jump squats at 30% of their 1RM squat (number of repetitions not noted).
The control (non-training group) maintained their usual activity routines.
The total amount of work between each training group was configured to be approximately the same, which results in the slightly different training protocols between groups and both groups trained twice per week.
All three groups were instructed no to perform any additional explosive type training during the training period, such as sprinting or Olympic lifting.
Before and after the training period tests were carried out on all participants on their Agility (T-Test), straight line speed (20m Sprint Test), electromyography (muscular electrical signals), strength (1 Repetition Maximum Squat) and vertical power (jump squat) at 30%, 55% and 80% of 1RM Squat.
In the jump squat testing the subjects were tested for peak force, peak velocity and peak power, jump height and work.
Neither group showed a significant difference between the numbers of workouts, sets or reps performed but the heavy training group did significantly more work than the light training group although there were no correlations found between the relevant performance variables and work performed. Both groups significantly improved their 1RM squat during the training period by around the same amount (the heavy training group increased their squat on average by 3kg more than the light training group).
At 30% or 1RM the light training group improved peak power, peak velocity and jump height however the heavy training group significantly increased peak force.
In the 55% of 1RM testing conditioning the light training group increased peak force, peak power and peak velocity.
In the 80% of 1RM testing condition the light training group increased peak force, peak power and peak velocity where the heavy training group only increased peak force and peak power.
In the agility tests both training groups significantly decreased their time.
In the sprint tests the heavy training group significantly increased their time over the first 5m but there was no significant difference between the groups in the other distances of the sprint test.
The EMG data showed that there was significantly more electrical activity for the the light training group in the light testing conditions and significantly more electrical activity for the heavy training group in the heavy testing condition. Both groups significantly increased muscular electrical activity in comparison with the control group at 55% and 80% testing conditions but only the light training group increased their muscular electrical activity at the 30% testing condition.
The findings of this study indicate that training adaptations are velocity specific as has been indicated by other studies. The underlying training principle demonstrated here is that specificity is key and as a coach it is important to decide upon the qualities that you wish to train. Where movement velocity is paramount then training light and fast is the most appropriate training mode.
In sports where athletes must also overcome significant weight such as in rugby, American football and Olympic weightlifting then training heavy and fast would seem appropriate to the demands in the sport as key factors to performance include developing a large force quickly. Again this needs to be considered with in the context of the players position where a prop forward (rugby) or a lineman (American football) will need to generate a high peak force as they need to overcome heavy and strong opposition. Alternatively a winger (rugby) or a running back (American football) will need to generate high peak velocity as sprint speed is crucial to success for these positions.
An interesting finding was that the intention to move quickly was not successful in improving peak velocity which is converse to Behm and Sale’s finding. What is more important from this study is that the actual movement itself is rapid.
From the results of this study the main conclusion seems to be that training at a low weight and thus high velocity will develop improved velocity, in activities such as sprint speed, agility, throwing and jumping.
These developments may not be useful for athletes who need to generate a high force rapidly in activities such as scrummaging or line out lifting in rugby but will be useful for line out jumpers in rugby or positions in various sports that require high movement velocity with low resistance such as sprinting, throwing or other jumping activities.
McBride, J. M., Triplett-McBride, T., Davie, A. & Newton, R. (2002). The effect of heavy- vs. light-load jump squats on the development of strength, power and speed. Journal of Strength and Conditioning Research, 16(1). 75-82.
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Plyometrics Part 1 - Part 1 of our 2 part plyometrics article covers some of the theory involved in this type of jump training.