Machines as an alternative to free weights
Leg press training to improve power and speed performance in inexperienced athletes
Replacing free weight strength exercises with a leg press is a viable alternative for injured or inexperienced athletes.
Overland Park, KS
Performance gains in standard tests such as the vertical jump and 20 yard dash are often attributed to gains in strength and power, which is primarily achieved in a weight training environment. Sometimes, inexperienced athletes are expected to train with heavy free weights, as training with machines such as the leg press is not considered to be “functional.”
This two-subject case study looks at a program intervention that substitutes leg press exercises for three free weight strength exercises, and examines its ability to effectively transfer strength and power to athletic performance.
Subject 1 in our case study is a college softball player who experienced discomfort in her low back during the final weeks of her spring season as her team performed their initial off-season performance testing. Knowing that she would be required to perform these exercises again upon her return to school in the fall, this subject was seeking an alternative program that would improve her speed and jumping ability without aggravating her lower back.
Subject 2 was a college soccer player who had never been diagnosed with a lower back injury, but commented on how heavy back squat exercises can sometimes result in soreness in her lower back. She felt that her limited experience in this heavy, free weight exercise (which quite often resulted in soreness) limited her ability to perform at an optimal level on the pre-season testing her team would be required to perform upon her return to school.
These two subjects took part in a summer program for college athletes where they would replace back squats, cleans and deadlifts with leg press exercises performed on a Cybex Eagle Leg Press. These subjects were healthy at the start of this program and had no discomfort in the program pre-tests.
The 8-week program consisted of a 4-day training split, where 2 days of strength training would be alternated with 2 days of speed, agility and conditioning. A typical week is shown in Table 1 in the appendix. The subjects performed the same exercises as college teammates, with the only exception being the substitution of leg press for back squat, hang clean and deadlift. When their programs called for these exercises, the subjects would perform the leg press exercises with the same sets and repetitions as the program required so as not to alter training volume. Periodization is shown in Table 2.
Table 1. Layout for the 4 day/week summer training program
Table 2. Weekly progression of leg press exercises during the eight week study
1L DB RDL – One leg Dumbbell Romanian deadlift to upright row, 2LP - Two Leg Press, 1LP - One Leg Press
On days where the program called for back squat and deadlift, the subjects would perform the leg press first as a double leg exercise in place of the back squat, and then as a single leg exercise in place of the deadlift. When the workout called for hang cleans, the subjects would alternate leg press with a single leg dumbbell Romanian deadlift (RDL) to upright row in superset fashion. This exercise was not done for speed, but instead emphasized rhythm, posture, balance and control.
Both subjects improved their vertical jump, standing long jump, and 20 yard dash performances following this training protocol (Table 3). Subjects commented after the study that they were experiencing no discomfort, and felt as if they could perform the speed and agility exercises with maximal effort.
Table 3. Improvements in five performance measures due to training program.
Upon completing the jumping and sprinting tests, both subjects tested their back squat 1RM. Neither subject showed an increase in 1RM in the back squat. And both subjects reported no pack pain or soreness other than mild, but tolerable, hamstring soreness in the days following maxing out on the back squat. Although neither subject increased in the back squat, both showed increases in the leg press. This may be because the back squat is highly technical, thus improved technique with practice would be valuable for someone with little experience squatting.
As is true of most college summer programs, heavy back squats, hang cleans, and variations of deadlift activities seem to be a primary focus of the off-season training program. Although improving one’s strength in these exercises is often linked to improved performance in speed and jump based testing, these exercises are also commonly contraindicated for those with back pain. The technical nature of these activities can also limit the amount of weight an athlete can use, which can therefore limit the level of power improvement, thus negatively affecting speed and jumping tests.
Although many strength and conditioning professionals will argue that free weight training provides superior results in speed and power tests as compared to training with machines, the results of this case study suggest that the Cybex Eagle Leg Press is equally effective at developing strength and functional outcomes as traditional, free weight-based exercises.
Although many coaches may still may encourage the to use of free weight exercises to lay the foundation for athletic performance, situations may present themselves from time to time when an athlete may have to alter the exercise selection over the course of the season. Inexperienced lifters, or those athletes that have pain and/or discomfort when performing traditional free weight exercises, may still be able to achieve gains in performance through the use of machines as they learn and develop the technical efficiency necessary for more complex lifts.
Machines can provide strength and conditioning professionals a means by which to train strength at maximal levels, and should be considered a viable alternative to free weight training. As this study shows, athletes can still observe noticeable gains in performance, while continuing to train with their team by altering the exercise selection.
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