I've been teaching Step Aerobics since 1992 - longer than any other class format. It is my favorite class. (I'm starting to like Spinning/Indoor Cycling almost as much.) Over the years, my fellow-instructors have felt the pressure from very experienced members to increase the music tempo and the complexity of choreography. The AFAA guideline indicates that 126 bpm is the maximum tempo for experienced participants, regardless of fitness level. Tempos exceeding 126 bpm exclude inexperienced members or people with physical limitations and, most importantly, studies show that increasing the tempo is not a directly proportional affect on increased intensity.
There are three issues to consider: aerobic range and thresholds, effects of music tempo, and teaching to the general population of our members.
I think the third issue is the most important one to consider. We have to teach to the general population so that we don't exclude new exercisers. Experienced exercisers should know what they need to do to increase the intensity of their workout and exactly where they should be working according to their individual goals (fat burning, cardiovascular fitness, endurance, etc). Our members are not elite athletes. We could have a specific class for that, but most classes should be tailored to our general member population.
Increased music tempo is not directly proportional to aerobic intensity!!! Here's the information from the AFAA Step Training Manual for the AFAA Step Certification I took in December 2005.
MUSIC TEMPO AS A VARIABLE TO MODIFY EXERCISE INTENSITY
Stanforth, D., Velasquex, Stanforth, P.R., Univerity of Texas at Austin, 1991. The Effect of Bench Height and Rate of Stepping on the Energy Cost of Bench Stepping.
Study: Twenty eight females performed step aerobics for 4 consecutive 5-minute sessions on 6-, 8-, 10- and 12-inch steps. The subjects performed an alternating-lead basic step at a randomly assigned tempo of 120 or 128 bpm. Hands were placed on the hips to avoid false elevation of heart rates. Oxygen consumption and heart rates were measured continously throughout exercise.
Findings: A step tempo increase from 120 to 128 bpm provided an increased oxygen cost of 1.5 ml/kg (.43 METS). This increase is minimal when compared to the additional 4.4 ml/kg oxygen consumption provided by a 2-inch rise in step height.
Olson, Michele and Williford, Henry, Step Aerobics Tempo Study, Sports Medicine, March 1996.
Study: A 10-week step aerobics research study was conducted at Auburn University at Montgomery (AUM) to examine step cadence and related physiological and biomechanical considerations. During a 10-week period, a group of women with similar fitness levels and experience performed 50-minute sessions (which included 30 minutes of step aerobics) three days per week.
Findings: Results of the study showed that at 128 bpm, all participants were able to maintain proper technique and perform the routine with minimal increases in vertical ground reaction forces. Cardiorespiratory demand increased by 5-15%. At 120 bpm on an 8-inch step, vertical ground reaction forces were recorded at 1.55 times the body weight. At 130 bpm, biomechanical stresses were observable. At 132 bpm, vertical ground reaction forces were 1.85 times the body weight. As a result of this study, Olson (36) suggests that although a cadence of 118-122 bpm provides more than sufficient exercise intensity, the research supports 122-128 bpm as the "ceiling of limitation" for step aerobics.
CONCLUSION
Although increases in step tempo provide an additional energy cost during exercise, the increase is minimal when compared to other variables examined. Be aware safety may be compromised at faster tempos, as proper form and technique are more difficult to achieve. Evaluate the risk/benefit ratio of increased music tempo and select a music tempo that allows class participants to execute the movements in proper form.
Guidelines currently recommend a stepping cadence of 118-122 bpm to provide sufficient physiological stimulus and allow participants to maintain proper form and body alignment. (9) This guideline is appropriate for the general population in the group exercise setting. The skilled and highly conditioned stepper may be able to amintain form and technique at slightly faster tempos--up to 126 bpm. Continually monitor your class. Be aware of participants' form and adjust tempo accordingly.
EFFECT OF POWER vs TRADITIONAL STEP AEROBICS
Greenlaw, K., et al., Medicine and Science in Sports and Exercise, Vol. 27, No. 5, June 1995, Abstrat #1343. The Energy Cost of Traditional Versus Power Bench Step Exercise at Heights of 4, 6, and 8 Inches.
Study: 18 subjects performed equally-choreographed videotaped routines of either traditional (low impact) or power (propulsion) step movements on step heights of 4, 6, and 8 inches. Movements included a basic step, turn step, alternating knee lift, kick back and over the top.
Findings: Energy cost (measured by heart rate and oxygen consumption) of all power movements was more than the traditional step movements. The heart rate was higher by 15-20 bpm, and oxygen consmption levels rose by 1.8 - 2.3 METs.
Step Height = 4
Heart Rate / VO2 ml/kg/min / METs:
traditional step movements - 138 bpm / 26.5 / 7.6
power step movements - 158 bpm / 34.5 / 9.9
Step Height = 6
Heart Rate / VO2 ml/kg/min / METs:
traditional step movements - 144 bpm / 29.0 / 8.3
power step movements - 163 bpm / 37.0 / 10.6
Step Height = 8
Heart Rate / VO2 ml/kg/min / METs:
traditional step movements - 155 bpm / 32.4 / 9.3
power step movements - 170 bpm / 38.7 / 11.1
CONCLUSION
Choreographic variables such as lever length, range of motion, elevation, traveling, arm movements and the inclusion of power movements will affect intensity. Select movements that are appropriate for the skill and fitness level of your class.
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My personal conclusion: I will not exceed 126 bpm and I will teach my participants about working within their aerobic range according to their personal goals. I will teach choreography that our general population can follow. I don't want to exclude our general population because a smaller group of more vocal (uneducated) members insists that we should teach at higher tempos and more complex choreography.
Just because we instructors and some of our members have been doing step for over 10 years, in many cases, we can't forget that their are still many people that are new to step or would like to try the class. We can't exclude them by design.