FitBits
September 15, 2007
Exercise ETC’s Review of Exercise Related Research
Compiled by Chris Marino, MS, CSCS
Director of Education, Exercise ETC
Planning on Pregnancy? Strengthen that Pelvic Floor!
The pubococcygeus muscles, which make up the pelvic floor have several important roles and can experience dysfunction during or following pregnancy (i.e. urinary incontinence, sexual performance, and spinal stabilization). Pelvic floor muscle exercise (PFME), often referred to as Kegels, have been advocated for decades to improve recovery of the pubococcygeus muscles following pregnancy. Interestingly, very few women actually practice them regularly if at all.
A recent study reported that 24% of pregnant women report urinary incontinence, yet only 17% utilize Kegel exercises regularly. So, why don’t more women using Kegels as a preventive strategy pre- and post-pregnancy?
Some researchers and doctors have questioned their effectiveness. However, a study published this month in the journal Clinics reported that women who performed regular Kegel exercises during pregnancy, regardless of dysfunction, did in fact improve the strength of their pelvic floor muscles 47.4% vs. 17.3% in controls.
The answer to the lack of PFME practice may not be physiological or mechanical, but educational. A recent study reported that only 64% of pregnant women surveyed were taught PFME. Racial and ethnic disparities were identified, since a greater number of white (75%) and Asian (48%) women were taught PFME compared to black (36%) and Hispanic (39%) women. In addition, 74% of those receiving education possessed a college degree, whereas 37% were without education. Of note, a high percent of those taught PFME continued to practice the exercises after delivery (68%) and 6 months later (63%).
This research presents a great opportunity for maternity fitness programs that include the education and practice of PMFE.
Oliveira, C.D., et al (2007) Effects of pelvic floor muscle training during pregnancy. Clinics. 62(4):439-446.
Bo, K., et al (2007) Do pregnant women exercise their pelvic floor muscles? International Urogynecological Journal of Pelvic Floor Dysfunction. 18(7): 733-736.
Fine, P., et al (2007) Teaching and practicing of pelvic floor muscle exercises in primiparous women during pregnancy and the postpartum period. American Journal of Obstetrics and Gynecology. 197(1):107-115
Over-speed Training Improves Function in Older Women
The decline in speed and efficiency of gait is one consequence of aging that can result in poor functional capacity and increase the risk of inactivity-related disease. Improving speed and decreasing the energy demands of walking could significantly improve quality of life among older adults. A recent study reports a unique strategy to accomplish this.
Researchers incorporated body weight unloading using a gait treadmill to exercise a group of 75 to 85 year old women at high speed and intensity over 12 weeks.
During the initial six weeks the group completed interval sessions on a treadmill with 40% body weight unloading at a speed equivalent to the ventilatory threshold (Tvent). Tvent is the point at which breathing begins to become labored. Intervals consisted of 4 sets of 5 minutes alternating 1 minute at Tvent with 1 minute of recovery walking speed.
Speed was increased over the first six weeks after which body weight unloading was reduced to 10% for the final 6-weeks of training. The researchers evaluated energy cost and speed of over-ground walking before and after 12-weeks of training.
The results indicated that energy cost at slow, comfortable and fast walking speeds decreased up to 21%. In addition, maximal walking speed and mechanical power output at Tvent increased, 13% and 67%, respectively.
This study represents a breakthrough in training for older adults. Therapeutic exercise programs aimed at reducing risk of falling and increasing function in older adults should consider the methods used in this study for practical application.
Thomas, E.E. et al (2007) Speed training with body weight unloading improves walking energy cost and maximal speed in 75-85 year old health women. Journal of Applied Physiology. Sept (Epub ahead of print)
Can the Elliptical Cross-trainer Really Save Your Joints?
Many fitness professionals are quick to recommend Elliptical Exercise (EE) for the client or individual with lower extremity joint pain or impact intolerance. Although ground reaction forces that occur with walking are lessened during EE, questions remain concerning the impact EE has on hip and knee kinematics, which might pose a greater risk to some of those same clients.
Researchers in Taiwan studied the kinematics of EE and compared it to that of level treadmill walking. Fifteen adult males were analyzed while walking on a treadmill and during EE. Controlling for cadence and step length, researchers analyzed 3D kinematic data, pedal reaction forces, and ground reaction forces during each condition.
Their findings reaffirmed that EE produces lower pedal reaction forces and loading rates compared to treadmill walking. EE did, however produce greater hip flexor and knee extensor moments potentially creating higher mechanical stress at those joints compared to treadmill walking.
The results of this study suggest that greater caution is necessary when recommending EE for clients. The researchers recommend that muscle strength and joint function be evaluated prior to using EE to reduce and avoid injuries.
Lu, T.W. et al (2007) Joint loading in the lower extremities during elliptical exercise. Medicine and Science in Sports and Exercise. 39(9): 1651-8.
Are You Losing Calcium When You Sweat?
The benefits of exercise in the prevention of osteoporosis are well known, but could exercise actually increase the risk by depleting calcium? A recent study reported that men lose significant amounts of calcium during strenuous exercise through increased sweating. To determine whether a similar loss occurs in women, researchers at Purdue University evaluated calcium changes over 24-hours after 60 minutes of strenuous exercise in young athletic women. They also assessed the effectiveness of calcium supplementation in preventing a net loss of calcium over that same time.
Twenty-six pre-menopausal women participated in three 8-day intervention phases: Placebo + no exercise, placebo + exercise, and 400 mg of calcium as calcium carbonate (TUMS ultra) twice daily and exercise.
The results confirmed previous findings in men whereas exercise was determined to have increased calcium losses via sweat. The researchers reported that urinary calcium excretion was higher during the calcium supplementation phase. This is suggested to represent higher net calcium absorption. In addition, urinary calcium excretion was unaltered with exercise. Hence, the body does not appear to compensate for calcium losses via sweating. The most important and practical finding was that net calcium retention was positive only when exercise was supported with calcium supplementation.
It remains questionable whether additional calcium over and above the daily recommendation of 1,000-1,500mg is appropriate, as this study controlled calcium intake minus supplementation well below this value. However, this study does validate the importance of maintaining adequate calcium intake to support potential exercise losses.
Martin, B.R., et al (2007) Exercise and calcium supplementation: effects on calcium homeotasis in sportswomen. Medicine and Science in Sports and Exercise. 39(9):1481-6.
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