These top researchers looked at how 35 healthy, active women would go performing bench step aerobics (BSA) as well as adding resistance training exercises. Four equally matched groups were set up. One group did 25 minutes of BSA only called group A25. Another group did 25 min of BSA plus sets of upper and lower body resistance training called group AR. Then a third group performed 40 minutes of BSA only called group A40. A fourth "control group" was also set up that did nothing but daily tasks (C).

They studied these groups of women and individualized their training for a period of 12 weeks. Of course before the training protocol began they were subjected to many tests and also performed the same tests after the 12 week exercise period, to establish changes due to exercise.

All of the fitness training groups improved their cardiovascular performance as measured by a VO2 (volume of oxygen used) max text. Post-workout heart rates improved significantly, which means decreased, in the A25 and AR groups.

Significant reductions in diastolic blood pressure were observed for the AR and A40 groups. While all exercise groups decreased systolic blood pressure in response to a maximal exercise test, only the AR group showed a significant decrease. The ratings of perceived exertion of each exercise, measured by the RPE scale, were significantly decreased for the A25 and AR groups only. As expected, the control (non-exercise) group recorded no changes over the 12 week period.

Muscular performance data showed that the AR group increased their squat and shoulder press weight by 26 and 11% respectively. Those performing aerobic only exercise, the A25 and A40, showed insignificant improvements by 9 and 16% respectively in the squat and only 5% in the shoulder press for both groups.

Only the AR group significantly improved their cycle time to exhaustion. Only the AR group showed a significant improvement of 30% in shoulder power. And only the AR group showed a significant improvement in peak vertical jump power.

In terms of body composition, no significant differences were observed in any of the training groups. All exercise groups lost significant bodyfat. Strong trends did show that those in the A40 and particularly those in the AR groups actually increased fat free mass (or muscle) but they were not statistically significant. Perhaps this will help ease the fears of some women exercisers who believe that resistance training will get you looking big and muscular. After 12 weeks of supervised resistance training these women gained only small amounts of muscle mass. In fact the researchers would have loved more muscle gain in these women since more muscle is associated with lower bodyfat levels and enhanced prevention of gaining weight.
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When looking at the muscle itself using MRI technology, one of the most sophisticated and precise measurement for muscle cross sectional area (CSA), the AR group significantly increased the CSA of the rectus fermoris and the vastus lateralis. Further probing also showed that the AR group only, increased the CSA of the hamstrings, particularly the bicep fermoris and semitendinosus muscles. The AR group only also improved the CSA of other leg muscles such as the adductor and the gracilis muscles.

So in summary, adding resistance training to your aerobics exercise schedule can bring added benefits that are especially important to women. An aerobic exercise program alone seems to lack the ability to develop muscle strength and power which are critical to the healthy woman. Developing these will greatly aid in the prevention of falls, aging, improve bone health and enhance performance including daily tasks.

This study clearly demonstrates the importance of resistance training in an effective health fitness program. Adding resistance training allows you to have lower heart rates after training and helps lower your blood pressure and thus lowers your risk of heart disease. Adding resistance exercise to your training program also seems to allow your body to work at a lower "stress" level not only by lowering blood pressure, heart rate but perhaps most importantly, your perceived level of exertion will be much more tolerable and maybe even enjoyable.

The study not only shows health benefits associated with adding resistance training. It also shows that daily tasks will be much easier, especially when it comes to balance, stability and muscular strength. Clearly those in the resistance exercise group actually were much stronger, in both the lower and upper body and in almost all instances tested better after the 12 weeks, compared to aerobics training alone. Even though this study found that body composition did not change significantly amongst groups, I'm certain that if they studied these women over a longer period of time, these women would have a more functional life and a better chance of being lean, and more importantly staying lean long term.