Life Fitness has introduced the 9500HR Cross-Trainer--Total Body System, a revolutionary total body cross-training machine that offers a new, virtually no-impact, highly efficient exercise. To establish the biomechanical benefits of the Cross-Trainer, Life Fitness commissioned Dr. Ann Ward and Dr. Kreg Gruben of the University of Wisconsin at Madison to conduct a formal empirical research study to analyze the benefits of cross-training and the specific capabilities of the Life Fitness Cross-Trainer--Total Body System.

Key findings derived from this and other studies are:

• The Cross-Trainer provides more aerobic work than treadmills, stairclimbers, rowers and skiers at comparable low levels of perceived exertion*
• The Cross-Trainer provides the high aerobic and muscular demands of running with the low impact of walking
• The Cross- Trainer provides 4 to 5 times more quadriceps, hamstring and gluteal muscle involvement than walking
• The Cross-Trainer is capable of involving all of the major muscle groups as shown by EMG testing
• Forward motion puts greater demands on buttocks and hamstrings
• Backward motion puts greater demands on calves and quads

Dr. Ward investigated the rate of energy expenditure at different resistance levels. This work created the formula allowing Life Fitness to give the most accurate caloric feedback possible to users of the Cross-Trainer.

Dr. Gruben studied the kinetics of the Cross-Trainer and all of the various components which are responsible for its unique motion. These components included ground forces (measured by force transducers), joint moments (torques), and electromyography (average muscle activity). The parameters not only described the movement but allowed understanding of its cause. Their shape and magnitude were used to compare cross-training to the same kinetic factors in walking, running and cycling.

The greatest advantage of the Cross-Trainer is the ability to solicit varied muscular demand throughout all major muscle groups of the body in a closed kinetic chain. The variety of muscular demand comes from:

• Different ranges of motion
• Forward motion putting greater demand on gluteals and hamstrings
• Backward motion putting greater demands on calves and quadriceps
• Using both arms (more muscle mass) or no arms
• Keeping elbows close (more triceps/biceps) or away (more pecs/back) from body
• Adjustable resistance/work rates

Cross-training imposes lower forces on the body's structures proportional to the greater aerobic benefits (higher calorie burn), often at lower perceived exertion than comparable intensities of running. Using arms and going forward burns the most calories and uses the most power with lower RPE (rate of perceived exertion).

Major muscle involvement averages up to 60% depending on the mode chosen (resistance level, forward or backward, arms or no arms). The only exception are the abdominals, which average from 4% to 10% during different modes, but show significant variability between users. The abdominals' main function is to maintain dynamic balance, stability and posture.

Cross-Trainer Workout Compared To Cycling*:

• Ground reaction forces are about 2 times greater than cycling at equivalent RPMs & workloads because the Cross-Trainer is a weight-bearing activity and cycling is not.
• In general, peak lower-limb muscular activity is comparable, with gluteal activity being greater, especially while going forward.
• Aerobic demands are relatively equivalent.

Therefore, with only a slight increase in loads on the body's structures (low impact), the Cross-Trainer provides a very similar muscular and aerobic workout with a somewhat greater involvement of the gluteus. It also provides the added benefits of weight-bearing exercise.

Cross-Trainer Workout Compared To Walking*:

• Foot forces are generally similar. Therefore, even at high resistance levels affording high aerobic and mechanical work, the Cross-Trainer is a Iow impact and Iow force exercise.
• Peak lower-limb muscular activation has been shown to be greater. Therefore, the Cross-Trainer could offer a better muscular workout with workloads that are comparable. Gluteus 4 times greater than walking
  Quadriceps 4.5 times greater than walking
  Hamstrings 5 times greater than walking
  
• Aerobic demands are substantially greater.

Therefore, for very similar loads on the body's structures, the Cross-Trainer offers a greater muscular workout and a much greater aerobic workout (calorie usage) than walking.

Cross-Trainer Workout Compared To Running*:

• All ground reaction force components are significantly smaller, ranging from 1.5 to 5 times less depending on the force.
• Peak muscular activity is no more than 1.7 times smaller, possibly due to greater eccentric force generated while running from the absorption of larger impact forces.
• Aerobic demands are only slightly smaller.

Therefore, for substantially less stress on the structures of the body (low impact) the muscular and aerobic challenge of the Cross-Trainer is comparable to running.

Life Fitness tested Cross-Trainer prototypes in clubs around the country for several months prior to introduction. Hundreds of members tested the product, putting some 3,794 hours on the prototypes over the course of 13,739 workouts. The Cross-Trainer averaged 7 hours of use - that's 30 workouts a day - in these high-traffic facilities during the testing period. From surveys completed by those users, Life Fitness refined and improved the product to its current form. Here are some of the facts discovered in the field testing research:

• Total body workout was the #1 reason cited for trying and continuing to use the product.
• "Smooth" was the most commonly used word in describing the product.
• Respondents cited interactive heart rate programs as a favorite feature of the machine, second to total body capability.

*Direct comparison between values has been made with great care due to differing intensities, testing protocols, and numbers of subjects, especially in the subjective measure of RPE.

Dr. Gruben's research entitled "Instrumentation and data acquisition system for assessment of exercise machine biomechanics" has been accepted for publication in the scientific journal Biomedical Instrumentation and Technology.

Life Fitness Cross-Trainer 9500HR University Research Study Findings--rev. 6/15/97