The effects of a Three-Week Power Training Program Using the Cybex Arc Trainer on Maximum Back Squat Strength
Replacing a lower body strength training routine with an Arc trainer power program resulted in increased maximum squat strength in a subject with lower back pain.
Overland Park, KS
Cardio cross trainers are typically associated with energy expenditure, calorie burn, and weight loss. One cardio product, however, has characteristics that may contribute to strength gains. The Cybex 750A Arc Trainer is a lower body cardio device that enables users to generate power up to 900 watts. Since higher power correlates with increased rate of tension development and strength gains, it is possible that training on the Arc Trainer at elevated power levels may result in improved strength outcomes.
In this case study, a subject’s normal strength training program was replaced with a power training regimen on the Cybex Arc Trainer to determine if it would improve his back squat one repetition maximum (1RM).
The subject is a 36 year-old, recreationally active male. Over a period of three months in 1997, the subject was struck by a motor vehicle and fell off a 2.5 story roof, landing on his feet. Neither incident resulted in fractures, but he did suffer severe back pain as a result. In 2006, while playing basketball, he again injured his back. Magnetic resonance imaging showed no fractures, but revealed a complete degeneration of the L5-S1 intervertebral disk.
Following conservative treatment and recovery, he began strength training 2-3 times per week. His post injury exercise regimen included performing back squats, and after twelve months, he reached a 1RM plateau of 265 pounds. Although the subject did not experience discomfort at this work load, any additional weight did induce pain in his lower back. The subject concluded that it was lumbar discomfort that limited his strength gains, and not lower body weakness.
In deciding to seek other forms of training, to help augment his lower body strength, the subject was introduced to the Cybex 750A Arc Trainer, and was shown how to manipulate speed and resistance in order to modify power during exercise sessions. He then opted to replace his normal lower body strength training routine with a 25-30 minute power program on the Arc Trainer.
The Arc Trainer protocol consisted of three power sessions per week, for a period of three weeks (Table 1). The exercise intervention was structured as follows:
Day 1: The subject completed two sets of five to eight power intervals (repetitions), following a 20 seconds work to 100 seconds rest format. Exercise cadence was fixed at 170 strides per minute, and resistance was increased after each interval, thereby increasing power, as fatigue allowed. If he was unable to maintain the required cadence for the full twenty seconds, resistance and power were decreased. Five intervals per set were performed during week one, six per set in week two and eight per set in week three. Five minutes of active recovery were taken between sets. Power output ranged from 400-700 watts per interval.
Day 2: The subject performed fifteen intervals of 60 seconds work to 60 seconds rest during a 30-minute workout. The objective was to increase the resistance every working minute as long as the subject was able to maintain a cadence of 120 strides per minute for the entire minute. Resistance was increased from a setting of 80% on the first week to a setting of 90% by the end of week three.
Day 3: The third workout of each week consisted of a three-minute on and one-minute off interval sequence, for 24 minutes. The resistance began at a setting of 35% and was increased to between 50% and 60% by the end of each session. No additional strength or fitness exercises were performed during this training period.
Table 1. Arc Trainer Strength and Power Protocol
Over the three-week period, the subject’s maximum back squat improved from 265 pounds to 285 pounds (Figure 1). He experienced no soreness in his back during, or following, the return to lifting. He further commented that the loads felt much better on both his legs and lower back. He chose to continue training on the Arc Trainer following this study, once per week for the next few months, and although not as substantial, he continued to record increases in his maximum back squat at a rate of approximately 5 lbs every 3 weeks.
After two months, and a brief wash-out period, the subject decided to repeat the 3-week protocol in order to validate the initial findings. The second time through the protocol the subject noticed a 15-pound increase in his 1RM, from 310 lbs to 325 lbs, again with no discomfort in the legs or lower back during squat testing. As seen in Figure 1, the subject’s rate of improvement was higher during the shaded periods.
Figure 1. Improvement in Back Squat 1RM over a ten month period (the shaded areas represent 3 week phases of power training on the Cybex Arc Trainer)
The subject entered the program with the expectation that strength would most likely decrease, and that he might see some gains in muscular endurance. He also assumed that once he returned to his strength training program, which involved heavy back squatting, he might feel discomfort in the lower back due to the lack of any core type strengthening during this three week period. These results are particularly interesting because the subject originally came to the conclusion that it was his lower back pain, and not necessarily lower body strength, that was limiting his maximum squatting ability. However, the results of this case study show that the subject was able to increase his maximum squatting weight as a result of the Arc Trainer protocol, without aggravating his lower back injury. These results suggest that the Cybex 750A Arc Trainer can be used as an effective strength-building tool, especially for individuals with chronic orthopedic issues.
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