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Bi-Directional Bike Pedaling System
"The difference of Lower Extremity Muscle Recruitment and Metabolic
Variables between Forward pedaling, Backward pedaling, and
Combined pedaling in Bicycle Exercise"

Research Institution:
Laboratory of Exercise Physiology of Seoul National University

Researchers:

How interesting is it to ride a bicycle by forward and backward pedaling interchangeably? MBI WORLD INDUSTRY CO. LTD., has developed a specially designed instrument, by which we can ride a bicycle with forward and backward pedaling, when it is attached to any bicycle. We can easily recognize that this system is good enough to attract the attention of people who love cycling. But how this system affects the bicycler's physiological response has not been verified. So we were asked by MBI WORLD INDUSTRY CO. LTD., to test the difference of physiological benefits between forward pedaling, backward pedaling, and combined pedaling exercise. For this interesting study, we focused on comparing muscle recruitment patterns, and metabolic variables such as VO2, energy consumption, efficiency, and lactate accumulation for the 3 types of pedaling.

Method
The subjects were 9 healthy male college students, divided randomly into 3 groups.  We also prepared a bicycle ergometer, (Monark SISE, Sweden) modified, to be loaded in both forward pedaling and backward pedaling. The technician from MBI WORLD INDUSTRY CO. LTD., helped us to do that. Each group member repeated 3 types of pedaling with the bicycle ergometer, in different order.  The first group performed forward pedaling, backward pedaling, and then combined pedaling.  The second group performed backward pedaling, combined pedaling, and then forward pedaling.  The third group performed combined pedaling, forward pedaling, and then backward pedaling respectively.

Each type of pedaling took 20 minutes with a load of 2.5kp (750kgm. 125watt), 50 rpm, and recovery intervals between each performance were held for 6 hours. For each of the 3 types of exercise, EMG analysis was done with vastus lateralis, biceps femoris anterior tibialis, and gastrocnemius muscles.  Also, the expired gas was collected to calculate V02 and R with a gas analyzing system. Blood samples were taken for calculating lactate accumulation. With the V02 and R we calculated energy consumption (Kcal/min), and efficiency.

For data analysis we used a one-way ANOV A and Duncan's multiple range test by means of an SPSS/PC program.

EMG Analysis
Muscle recruitment patterns in lower extremities were analyzed qualitatively by EMG, and appeared as shown in Fig 1. Vastus lateralis, Biceps femoris, Anterior tibialis, Gastrocnemius were all activated in both forward pedaling and backward pedaling. But Vastus lateral is contracted more forcefully in backward pedaling than in forward pedaling. On the other hand, Biceps femoris, the antagonist of Vastus lateralis contracted more forcefully in forward pedaling than in backward pedaling. Anterior tibialis analysis did not show a significant difference between forward and backward pedaling.  Gastrocnemius contracted more forcefully in forward pedaling than in backward pedaling.
 

Mean
Group
1 (Forward)
2 (Backward)
3 Combined
3.6750
1 (Forward)
**
**
**
6.4875
2 (Backward)
*
**
*
4.4000
3 (Combined)
**
**
**

Comment
With the results from EMG analysis, we were able to recognize that muscle recruitment patterns in lower extremities were not the same between forward pedaling and backward pedaling.  It was concluded that agonist muscles would be developed simultaneously by exerting those muscle forces interchangeably, even though there were no statistically significant differences in metabolic variables (VO2, energy consumption, efficiency) except lactate accumulation.  Lactate was highest and efficiency was lowest in backward pedaling. This indicated that backward pedaling was the hardest method of the 3 types of pedaling. This would be due to the unfamiliarity of backward pedaling. Although the difference didn't show a statistical significance, in combined pedaling VO2 and energy consumption was lowest, lactate accumulation was comparatively low, and efficiency was highest.

With these results we could predict that combined pedaling by agonist and antagonist muscles exerting force interchangeably had an effect on delaying muscular fatigue, with VO2 and energy consumption being statistically the same.

In conclusion, we recommend combined pedaling be used for well balanced muscular development.

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