Zhang J, Provencher S, Unger Jr JFWFC’S 10th Biennial Congress. International Conference of Chiropractic Research.  Montreal, CanadaApr 30 – May 2, 2009: 397-8


Background and Objectives: The ergonomics of bicycle riding for leisure or sports have been studied extensively. The traditional bicycle saddle exerts pressure on the underlying tissue that can cause low back pain, sciatica, numbness of the legs and feet as well as more complex problems, such as impotence in male riders. A new seat was designed to change the weight bearing areas in an effort to improve riding comfort and facilitate function of the craniosacral mechanism while minimizing the sacroiliac strain to increase efficiency. The aim of the present study was to assess the effects of riding a bicycle with the new seat on the sympathovagal control of heart rate variability (HRV) in normal human subjects as compared to the traditional saddle. The outcome assessment of the study was heart rate variability (HRV), an indicator of activity of the autonomic nervous system that has been used in healthy human subjects before and after bicycle riding.

Methods: Eighteen healthy human subjects participated in this randomized controlled study by riding a bicycle fitted with the new seat and the traditional saddle. The IRB was obtained by Logan College of Chiropractic. The HRV was evaluated using the Biopac 100 System for ECG recording before and after the bicycle riding each day for 15 minutes. Three HRV frequency bands (high, low and very low frequencies) and the total power were analyzed using DADiSP software.

Results: A significant increase in the heart rate was seen in both the new and traditional seat groups (P<0.05) after exercise. The mean heart rate in the new seat group was 79.90 @13.74 before and 90.74@18.73 (P<0.05) after riding on the bicycle. The total power and very low frequency band in the HRV analysis with the new seat did not show significant changes. The low frequency component and the high frequency component in the new seat group was significantly decreased from 1612.36 to 670.08 Hz^/s and from 304.65 to 131.16 Hz^/s after riding the bicycle. In the old seat group, the high frequency component increased from 230.10 to 257.51 after riding the bicycle. The low frequency band did not show significant changes in the traditional seat group.

Discussion: The effects of bicycling on HRV and cardiovascular functions have been investigated [1-2], but there is no report comparing the effects of two different bicycle seats on HRV. A poor bike seat design may not distribute body weight optimally [3,5] which may compress the neurovascular structures [4,5] and may affect the autonomic nervous system. The sympathetic nerve activity is represented by the high frequency component which showed no significant change in the traditional seat group compared to a decrease in the high frequency component in the experimental group. It was also noted that the low frequency component was significantly reduced in the experimental group. The ratio of reduction of the low frequency component was greater than the ratio of the high frequency component which suggests a reduction in parasympathetic activity.

Conclusions: The newly designed bicycle seat affected the subjects’ HRV in both the LF and HF bands while the traditional saddle did not. The major change in the HRV was a greater reduction of parasympathetic activity after riding. The current pilot study, while yielding interesting information, indicates that further studies are needed with a larger sample of subjects, a specific neurovascular4-5 and muscular testing and investigation of implication for the pelvic and sacroiliac joint biomechanics.

References:

  1. Lucia A, Hoyos J, Perez M, Chicharro JL. Heart rate and performance parameters in elite cyclists: a longitudinal study. Med Sci Sports Exerc 2000 Oct;32(10): 1777-82.
  2. Hautala A, Tulppo MP, Makikallio TH, Laukkanen R, Nissila S, Huikuri HV. Changes in cardiac autonomic regulation after prolonged maximal exercise. Clin Physiol 2001 Mar;21(2):238-45.
  3. Keytel LR, Noakes TD. Effects of a novel bicycle saddle on symptoms and comfort in cyclists. S. Afr. Med. J. 2002; 92: 395-298.
  4. Bressel E, Reeve T, Parker D, Cronin J. Influence of bicycle seat pressure on compression of the perineum: a MRI analysis. J. Biomech. 2007;40(1):198-202.
  5. Bressel E, Shantelle B, Cronin J. A field based approach for examining bicycle seat design effects on seat pressure and perceived stability. Applied Ergonomics, 2008.

A case study of a 38-year-old female with chronic otitis media and loss is presented. The symptoms subsided and hearing was restored through chiropractic care with an emphasis on cranial adjustments. Chiropractic treatment of chronic otitis media of adults and children as an alternative to tympanotomy and ventilation tubes is discussed.

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