Introduction

Methods

Results and Discussion

Conclusions

Notes

MECHANICAL AND ELECTROMYOGRAPHICAL TESTING OF THE AFTERBURNER® STRENGTH TRAINING SYSTEM

Results and Discussion:

AVERAGE FORCE: The first major finding of this study was that the subjects were able to perform the 10 repetitions at a higher average force with Afterburner® than they were in the traditional exercise.

When the resistance was set properly, subjects were able to start at a resistance of 115% of the 10RM value which linearly declined to 97% for an average of 107% of the 10RM. Figure 1 shows the forces of a typical subject during the two exercise sets and it can be seen that the forces started higher with Afterburner® (blue line) and finished at the same level as the 10RM forces (black line). The straight lines represent the trends during the 10 repetitions for each exercise.

Several subjects (particularly the less strong subjects) finished well below the 10-repetition level due to the flow rate being set too high. This error can be easily avoided by adjusting the valve to a setting that will only lose about the same weight of water as the added weights during the duration of the exercise set (i.e. 15% of the 10RM). For some users this will require some trial and error to find the correct initial weight and valve setting. The results of this study indicate that the first trial should have the initial weight set at 95% of 1RM and the valve should be set to a position that loses about 15% of 1RM over 30 seconds. This will require the tank to be calibrated for pounds of water. It may also be necessary for heavy load exercises to have a valve setting faster than the present valve maximum because loads greater than 200 pounds cannot lose 15% (30 pounds) in 30 seconds. Users who lift with a faster cadence and require less than 30 seconds to complete their set should also use a faster flow rate to lose 15% by the end of the set.

MUSCLE ACTIVATION: The results of the activation data (EMG) supported the hypothesis that the EMG would increase with fatigue during the 10RM.

This result is common and indicates that only the last repetition or two require the muscle to be most activated and therefore overloaded. The activation results of the Afterburner® sets were equivocal due to some subjects starting at loads that were too low and/or due to flow rates that were too high. However, it was seen in those subjects with appropriate settings for the Afterburner® set that the EMG values were greater at the beginning than the 10RM and that a greater portion of the ten repetitions were overloaded than during the 10RM. This supports the notion that the Afterburner® would allow the user to experience the same or greater overload with fewer repetitions and/or sets. Even though all subjects started with a higher EMG value, these values were never as large as the fatigued value of the 10RM and the EMG values did progress to higher levels by the end of the Afterburner® sets. The reasons for this are unclear at this time but it may be necessary for the muscle to experience fatigue before subjects are capable of maximum activation. Regardless of the cause, The Afterburner® set produced greater EMG and greater fatigue in the musclesof those subjects with appropriate load settings. Figure 2 shows the EMG results of the same subject shown in Figure 1. It can be seen that the 10RM activations (black line) increased with fatigue by the last repetition. The Afterburner® activations (blue line) started at a higher level and also increased with fatigue. It can be seen that the last three repetitions of the Afterburner® set had the same activations as the last repetition of the 10RM set.

This indicates that this subject would require three 10RM sets to achieve the overloaded activations of the last three repetitions of a single Afterburner® set.