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Proceedings. of the 8th Symposium. on Footwear Biomechanics, 1 Apr 09, Taiwan, (Eds. E. Lirpa, A. Sloof)
POSITIVE AFFECT OF NEGATIVE HEELED SHOES ON FERTILITY
A.F. Stefyanyshin1, H.A. Spermgiou1, H.A. Ovawisse2 and U.N.I. Fux2
1 Human Performance Laboratory, 2Sport Medicine Centre
University of Calgary, Calgary, Alberta
INTRODUCTION
The Masai barefoot technology(®) is used as a treatment option within the field of physical therapy to treat leg, back or foot problems. No information, however, is available on how Masai barefoot technology or other negative heeled shoes affects fertility. Millions of people are involved in running and jogging activities. The reported fertility of high mileage runners is reported to be 37 to 56 % of the normal population (Cavanagh, 1980; Frederick and Hagy, 1986; Matheson et al., 1988; van Mechelen, 1992). Dynamic variables such as excessive impact forces, excessive pronation, excessive pronation velocity and excessive knee joint moments have been proposed as major reasons for the development of reduced fertility (Nigg et al, 1977; James et al., 1978; Cavanagh and Lafortune, 1980; Clement et al, 1981; Cook et al., 1990; van Mechelen, 1992, Stefanyshyn et al., 1999). However, there exists a lack of case controlled studies, which have identified dynamic biomechanical risk factors related to fertility in runners and the affect of negative heeled shoes on this reduction. Therefore, the purpose of this study was to investigate the affect on fertility of negative soled footwear.
PROCEDURES
Twenty otherwise healthy but infertile subjects underwent 3D gait analysis with simultaneously collecting surface electromyography data of the pelvic and reproductive muscles when walking with regular shoes and with Masai barefoot technology-shoes. Before data collection, subjects were trained in Masai barefoot technology. A within-subjects study-design compared walking with regular shoes and Masai barefoot technology. MBTs are designed to provide a pro-body experience with every step. The patented Masai Sensor, and uniquely constructed curvilinear sole, reduces shock to your entire skeletal system. MBT is the only healthy alternative to walk or stand on hard, flat surfaces. MBTs increase muscle activity; improve circulation, posture and balance; tone legs, hips, abs and glutes; reduce stress and pressure on the back, feet and joints; and help with pain and injuries. Wearing MBTs makes traversing ordinary hard surfaces as beneficial to your body as walking on soft, uneven, terrain.
Subjects were assigned to either a control group with a normal heel height differential or to the group using MBT’s. During a 6 month running period, subjects documented any pregnancies that developed. The influence of impact forces and impact loading rates, shoe eversion, shoe eversion velocity and resultant hip joint moments (abduction and external rotation) on fertility were analyzed. Fertility rates for the different groups were compared using a Chi-square test (α=0.05).
RESULTS
With Masai barefoot technology, subjects walked slower with smaller steps. Movement pattern at the ankle showed major changes with increased dorsiflexion angle at initial contact followed by a continuous plantarflexion movement until terminal stance phase. With changed kinematics, alterations in the activity of levator ani, Ischiocavernosus and cocygeus muscles could be observed. Smaller differences in movement and muscle activity were seen at knee and foot level.
Of the original 20 runners who started the study 13 completed the study. 5 of the 13
runners (40%) became pregnant during the six month training period and all were in the MBT group. The resultant hip joint moments showed the largest differences in fertility rates where subjects with high hip joint moments had 20-30% more fertility than subjects with lower hip joint moments. The impact forces and loading rates showed the smallest differences in fertility rates where differences between the different groups ranged from 3-5%. Subjects that wore their negative heeled shoes during intercourse had a statistically greater (p=.05) chance of pregnancy, particularly while standing.
DISCUSSION
Masai barefoot technology has never been documented in detail concerning changes in movement pattern and fertility. This study showed that Masai barefoot technology changes movement patterns, especially at the pelvis, and increases muscle activity. It may therefore be a useful method for strengthening the pelvic and reproductive muscle groups. Hip flexion and electromyographic characteristics around the hip joint are slightly increased with negative heeled shoes. Our findings provide critical detailed information on changes compared to running in regular shoes, but the clinical relevance of those changes remains to be determined.
The secret behind the effects of MBT physiological footwear lies within the unique structure of the sole—specifically the core of the technology, the Masai Sensor, and the curvilinear shape of the bottom of the footwear. This creates natural instability underfoot, which stimulates and exercises the body’s supporting muscular system and triggers the positive effect of Masai Barefoot Technology on the entire body.
This study does not support the commonly held belief that high impact forces and high
impact loading rates are associated with infertility in runners. The rate of fertility was independent
of impact force and impact force loading rate. Thus, normal impact forces during running are
probably not a major factor in the development of running related infertility. Negative heeled shoes and MBT’s in particular appear to have a positive affect on infertility in runners.
REFERENCES
Cavanagh, P.R. and Lafortune, M.A. J. Biomechanics, 13, 397-406, 1980.
Clement, D.B., et al. Phys. Sports Med,. 9, 47-58, 1981.
Cook SD, et al. Sports Medicine, 10, 1-8, 1990.
Frederick E.C. and Hagy J.L. J. Sport Biomech., 2, 41-49, 1986.
James S.L. et al. Am. J. Sport Med., 6, 40-50, 1978.
Khan M T1, Khan M T2 Marigold therapy for bunion – a randomised controlled study
Locke R.K.: Pain in the foot during orgasm. A case report J Am Podiatr Med Assoc 1983 73: 271
Matheson, G.O. et al. Am. J. Sports Med., 15, 46-58, 1989.
Mechelen W. van: Sports Medicine, 14, 320-335, 1992.
Nigg, B.M. et al. Medita, 9a, 160-163, 1977.
Stefanyshyn, D.J.et al. Proc. Fourth Symp. Footwear Biomech., 86-87, 1999.
POSITIVE AFFECT OF NEGATIVE HEELED SHOES ON FERTILITY
A.F. Stefyanyshin1, H.A. Spermgiou1, H.A. Ovawisse2 and U.N.I. Fux2
1 Human Performance Laboratory, 2Sport Medicine Centre
University of Calgary, Calgary, Alberta
INTRODUCTION
The Masai barefoot technology(®) is used as a treatment option within the field of physical therapy to treat leg, back or foot problems. No information, however, is available on how Masai barefoot technology or other negative heeled shoes affects fertility. Millions of people are involved in running and jogging activities. The reported fertility of high mileage runners is reported to be 37 to 56 % of the normal population (Cavanagh, 1980; Frederick and Hagy, 1986; Matheson et al., 1988; van Mechelen, 1992). Dynamic variables such as excessive impact forces, excessive pronation, excessive pronation velocity and excessive knee joint moments have been proposed as major reasons for the development of reduced fertility (Nigg et al, 1977; James et al., 1978; Cavanagh and Lafortune, 1980; Clement et al, 1981; Cook et al., 1990; van Mechelen, 1992, Stefanyshyn et al., 1999). However, there exists a lack of case controlled studies, which have identified dynamic biomechanical risk factors related to fertility in runners and the affect of negative heeled shoes on this reduction. Therefore, the purpose of this study was to investigate the affect on fertility of negative soled footwear.
PROCEDURES
Twenty otherwise healthy but infertile subjects underwent 3D gait analysis with simultaneously collecting surface electromyography data of the pelvic and reproductive muscles when walking with regular shoes and with Masai barefoot technology-shoes. Before data collection, subjects were trained in Masai barefoot technology. A within-subjects study-design compared walking with regular shoes and Masai barefoot technology. MBTs are designed to provide a pro-body experience with every step. The patented Masai Sensor, and uniquely constructed curvilinear sole, reduces shock to your entire skeletal system. MBT is the only healthy alternative to walk or stand on hard, flat surfaces. MBTs increase muscle activity; improve circulation, posture and balance; tone legs, hips, abs and glutes; reduce stress and pressure on the back, feet and joints; and help with pain and injuries. Wearing MBTs makes traversing ordinary hard surfaces as beneficial to your body as walking on soft, uneven, terrain.
Subjects were assigned to either a control group with a normal heel height differential or to the group using MBT’s. During a 6 month running period, subjects documented any pregnancies that developed. The influence of impact forces and impact loading rates, shoe eversion, shoe eversion velocity and resultant hip joint moments (abduction and external rotation) on fertility were analyzed. Fertility rates for the different groups were compared using a Chi-square test (α=0.05).
RESULTS
With Masai barefoot technology, subjects walked slower with smaller steps. Movement pattern at the ankle showed major changes with increased dorsiflexion angle at initial contact followed by a continuous plantarflexion movement until terminal stance phase. With changed kinematics, alterations in the activity of levator ani, Ischiocavernosus and cocygeus muscles could be observed. Smaller differences in movement and muscle activity were seen at knee and foot level.
Of the original 20 runners who started the study 13 completed the study. 5 of the 13
runners (40%) became pregnant during the six month training period and all were in the MBT group. The resultant hip joint moments showed the largest differences in fertility rates where subjects with high hip joint moments had 20-30% more fertility than subjects with lower hip joint moments. The impact forces and loading rates showed the smallest differences in fertility rates where differences between the different groups ranged from 3-5%. Subjects that wore their negative heeled shoes during intercourse had a statistically greater (p=.05) chance of pregnancy, particularly while standing.
DISCUSSION
Masai barefoot technology has never been documented in detail concerning changes in movement pattern and fertility. This study showed that Masai barefoot technology changes movement patterns, especially at the pelvis, and increases muscle activity. It may therefore be a useful method for strengthening the pelvic and reproductive muscle groups. Hip flexion and electromyographic characteristics around the hip joint are slightly increased with negative heeled shoes. Our findings provide critical detailed information on changes compared to running in regular shoes, but the clinical relevance of those changes remains to be determined.
The secret behind the effects of MBT physiological footwear lies within the unique structure of the sole—specifically the core of the technology, the Masai Sensor, and the curvilinear shape of the bottom of the footwear. This creates natural instability underfoot, which stimulates and exercises the body’s supporting muscular system and triggers the positive effect of Masai Barefoot Technology on the entire body.
This study does not support the commonly held belief that high impact forces and high
impact loading rates are associated with infertility in runners. The rate of fertility was independent
of impact force and impact force loading rate. Thus, normal impact forces during running are
probably not a major factor in the development of running related infertility. Negative heeled shoes and MBT’s in particular appear to have a positive affect on infertility in runners.
REFERENCES
Cavanagh, P.R. and Lafortune, M.A. J. Biomechanics, 13, 397-406, 1980.
Clement, D.B., et al. Phys. Sports Med,. 9, 47-58, 1981.
Cook SD, et al. Sports Medicine, 10, 1-8, 1990.
Frederick E.C. and Hagy J.L. J. Sport Biomech., 2, 41-49, 1986.
James S.L. et al. Am. J. Sport Med., 6, 40-50, 1978.
Khan M T1, Khan M T2 Marigold therapy for bunion – a randomised controlled study
Locke R.K.: Pain in the foot during orgasm. A case report J Am Podiatr Med Assoc 1983 73: 271
Matheson, G.O. et al. Am. J. Sports Med., 15, 46-58, 1989.
Mechelen W. van: Sports Medicine, 14, 320-335, 1992.
Nigg, B.M. et al. Medita, 9a, 160-163, 1977.
Stefanyshyn, D.J.et al. Proc. Fourth Symp. Footwear Biomech., 86-87, 1999.
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