The Effect of Weight-Bearing Exercise on Bone Mineral Density: A Study on Female Ex-Athletics and the General Population

Dr. John Ethefington, London
St Thomas Hospital , London

The aim of this retrospective cohort study was to estimate the changes in bone mineral density (BMD) as a consequence of exercise in female ex-athletes and age matched controls. Eighty-three ex-elite female athletes (67 middie and long distance runners, 16 tennis players, currently aged 40-65) were recruited from the original records of their sporting associations. Controls were 585 age matched females. The main outcome measures were BIVID of lumbar spine (LS) femoral neck (FN) and forearm, estimated by DXA scan. Levels of physical activity were assessed using a modified Allied Dunbar Fitness Survey scale and classified as a) Ex-athletes b)

Active controls ( > 1 hour of vigorous physical activity currently and in the past) c) Low activity controls with inconsistent or intermediate levels of activity d) Inactive controls (<15 minutes exercise per week). Results: after adjustment for differences in age, weight, height and smoking, athletes had greater BIVIDs than controls; 8.7% at the LS (95% CI 5.4 – 12.0, p< 0.001) and 12.1% at FN (9.0 – 15.3, p< 0.001). The benefits of exercise appeared to persist after cessation of sporting activity. Active controls (n = 22) had greater BIVIDs than the Inactive group (n = 347) : 7.9% LS (2.0 – 13.8, p = 0.009) and 8.3% FN (2.7 – 13.8, p = 0.004). The Low activity controls (n = 216) had an intermediate BMD. Tennis players had greater BMDs compared to runners; 12.0% LS (5.7 – 18.2 p = 0.0004), 6.5 % FN (- 0.2 – 13.2, p = 0.066). The BIVID of Tennis players’ dominant forearms were greater than their non-dominant forearms. In conclusion, regular vigorous weight bearing exercise of one hour or more per week is associated with an increase in BIVID within a normal population. This study confirms long term weight-bearing exercise as an important factor in the regulation of bone mass and fracture prevention.

Limited Range-of-Motion Lumbar Extension Strength Training

James E. Graves, Michael L. Pollock, Scott H. Leggett, David M. Carpenter, Cecily K. Fix, and Michael N. Fulton

The purpose of this study was to evaluate the effect of limited rangeofmotion (ROM) resistance training on the development of lumbar extension strength through a 72° ROM. 33 men and 25 women (age = 30 ± 11 yr) were randomly assigned to one of three training groups or a control group (C; n = 10) that did not train. Training was conducted once per week for 12 wk and consisted of one set of 8­12 repetitions of variable resistance lumbar extensions until volitional fatigue. Group A (n = 18) trained from 72° to 36° of lumbar flexion; group B (n = 14) from 36° to 0° of lumbar flexion; and group AB (n = 16) from 72° to 0° of lumbar flexion. Prior to and after training, isometric lumbar extension torque was assessed at 72°, 60°, 48°, 36°, 24°, 12°, and 0° of lumbar flexion. Analysis of covariance showed that groups A, B, and AB increased lumbar extension torque (P 0.05) at all angles measured when compared with C. The greatest gains in torque were noted for groups A and B in their respective ranges of training but A and B did not differ from AB (P > 0.05) at any angle. These data indicate that limited ROM lumbar extension training through a 36° ROM is effective for developing strength through 72° of lumbar extension.

High Intensity Strength Training in Nonagenarians

Effects on skeletal muscle

Maria A. Fiatarone, MD; Elizabeth C. Marks, MS; Nancy D. Ryan, DT; Carol N. Meredith, PhD; Lewis A. Lipsitz, MD; William J. Evans, PhD

Muscle dysfunction and associated mobility impairment, common among the frail elderly, increase the risk of falls, fractures, and functional dependency. We sought to characterize the muscle weakness of the very old and its reversibility through strength training. Ten frail, institutionalized volunteers aged 90 ± 1 years undertook 8 weeks of highintensity resistance training. Initially, quadriceps strength was correlated negatively with walking time (r= ­.745). Fatfree mass (r=”.732)” and regional muscle mass (r=”.752)” were correlated positively with muscle strength.

Strength gains averaged 174% + 31% (mean ± SEM) in the 9 subjects who completed training. Midthigh muscle area increased 9.0% ± 4.5%. Mean tandem gait speed improved 48% after training. We conclude that highresistance weight training leads to significant gains in muscle strength, size, and functional mobility among frail residents of nursing homes up to 96 years of age.

Effect of Training Frequency and Specificity on Isometric Lumbar Extension Strength

James E. Graves, PhD, Michael L. Pollock, PhD, Dan Foster, BS, Scott H. Leggett, MS, David M. Carpenter, MS, Rosemaria Vuoso, MS, and Arthur Jones.

To investigate the effects of training frequency and specificity of training on isolated lumbar extension strength, 72 men (age = 31 ± 9 years) and 42 women (age = 28 ± 9 years) were tested before and after 12 weeks of training. Each test involved the measurement of maximum voluntary isometric torque at 72°, 60°, 48°, 36°, 24°, 12°, and 0° of lumbar flexion. After the pretraining teste, subjects were randomly stratified to groups that trained with variable resistance dynamic exercise every other week (1x/2 weeks, n = 19), once per week (1x/week, n = 22), twice per week (2x/week, n = 23) or three times per week (3x/week, n = 21); a group that trained isometrically once per week (n = 14); or a control group that did not train (n = 15). Analysis of covariance showed that all training groups improved their ability to generate isometric torque at each angle measured when compared with controls (P < 0.05).

There was no statistical difference in adjusted posttraining isometric torques among the groups that trained (P > 0.05), but dynamic training weight increased to a lesser extent (P < 0.08) for the 1 x/2 weeks group (26.6%) than for the groups that trained 1 x/week, 2x/week, and 3x/week (37.2 to 41.4%). These data indicate that a training frequency as low as 1 x/week provides an effective training stimulus for the development of lumbar extension strength. Improvements in strength noted after isometric training suggest that isometric exercise provides an effective alternative for developing lumbar strength.

Effect of Resistance Training on Lumbar Extension Strength

Michael L. Pollock,* PhD, Scott H. Leggett, MS, James E. Graves, PhD, Arthur Jones, Michael Fulton, MD, and Joe Cirulli.
Development of a new testing machine, which stabilizes the pelvis, allowed us to evaluate the lumbar extensor muscles before and after training. Fifteen healthy subjects (29.1 ± 8 years of age) trained 1 day per week for 10 weeks and 10 healthy subjects (33.7 ± 16 years of age) acted as controls. Training consisted of 6 to 15 repetitions of full range of motion variable resistance lumbar extension exercise to volitional fatigue and periodic maximal isometric contractions taken at seven angles through a full range of motion. Before and after the 10 week training period, subjects completed a maximum isometric strength test at seven angles through a 72° range of motion (0°,12°, 24°, 36°, 48°, 60°, and 72° of lumbar flexion).

The training group significantly improved in lumbar extension strength at all angles (P 0.01). The result at 0° (full extension) showed an increase from 180.0 ± 25 Nm to 364.1± 43 Nm (+102%) and at 72° (full flexion) from 427.4 ± 44.1 to 607.4 ± 68 (+42%) Nm. Results from the control group showed no change (P 0.05). The magnitude of gain shown by the training group reflects the low initial trained state of the lumbar extensor muscles. These data indicate that when the lumbar area is isolated through pelvic stabilization, the isolated lumbar extensor muscles show an abnormally large potential for strength increase.

Effect of Reduced Frequency of Training and Detraining on Lumbar Extension Strength

Jacqueline T. Tucci, MS, David M. Carpenter, MS, Michael L. Pollock, PhD, James E. Graves, PhD, and Scott H. Leggett, MS

To investigate the effect of reduced frequency of training and detraining on lumbar extension strength, 50 subjects (34 men, aged 34 ± 11 yrs; and 16 women, aged 33 ± 11 yrs) were recruited from ongoing strength training programs. Initial training consisted of 10 or 12 weeks of variable resistance lumbar extension strength exercise to volitional fatigue 1, 2, or 3 times a week. After the initial training, subjects reduced the frequency of training to once every 2 weeks (n = 18) or once every 4 weeks (n = 22) for 12 weeks. Only the frequency of training was changed; the mode, volume, and intensity of exercise remained constant for both reduced frequency of training groups. An additional ten subjects terminated training and acted as controls (detraining group). Isometric lumbar extension strength was evaluated at seven angles through a 72 degree range-of-motion before training, after training, and after reduced frequency of training or detraining.

Analysis of variance with repeated measures indicated that lumbar extension strength improved (P 0.05) for all groups after the initial 10 or 12 weeks of training. After 12 weeks of reduced training, the once every 2 weeks and once every 4 weeks groups showed no significant reduction in lumbar extension strength at any angle tested, whereas the detraining group demonstrated an average 55% reduction in strength. These findings indicate that isometric lumbar extension strength can be maintained for up to 12 weeks with a reduced frequency of training as low as once every 4 weeks when the intensity and the volume of exercise are maintained.

The Clinical Effects of Intensive Specific Exercise on Chronic Low Back Pain

A Controlled Study of 895 Consecutive Patients with 1 Year Follow Up

Brian W. Nelson, MD, Elizabeth O’Reilly, RN, Mark Miller*, PT, Mike Hogan, PT, Joseph A. Wegner, MD, MPH, Charles Kelly, MD

Focus on the Spine

Eight hundred ninety-five consecutive chronic low back pain patients were evaluated. Six hundred twentyseven completed the program. One hundred sixtyone began, but dropped out, and 107 were recommended for treatment but did not undergo treatment for various reasons. Average duration of symptoms prior to evaluation was 26 months. Fortyseven percent of patients were workers’ compensation patients.

The primary treatment was intensive specific exercise using firm pelvic stabilization to isolate and rehabilitate the lumbar spine musculature.

Patients were encouraged to work hard to achieve specific goals. Seventysix percent of patients completing the program had excellent or good results.
At 1year follow up 94% of patients with good or excellent result reported maintaining their improvement. Results in the control group were significantly poorer in all areas surveyed except employment.

Comparison of Female Geriatric Lumbar-Extension Strength: Asymptomatic Versus Chronic Low Back Pain Patients and Their Response to Active Rehabilitation

Bryon Holmes, Scott Leggett, Vert Mooney, Jean Nichols*, Scott Negri, and An Hoeyberghs

We compared lumbarextension strength between healthy asymptomatic geriatric females (HEAL) and symptomatic geriatric females (INJ) seeking medical attention for chronic low back pain. The INJ group used the MedX lumbarextension machine to perform isotonic exercise two times per week and were eventually reduced to one time per week, Range of motion (ROM) and strength were significantly different between groups before beginning the program. After the program, ROM and strength improved significantly and were not different from those of the HEAL group.

The average length of treatment was 97 days and 20 visits. Subjective pain ratings were significantly reduced (60%) and exercise weights significantly increased (71%). This reconfirms the notion that many back pain sufferers have weaker lumbarextension strength and that some symptomatic geriatric women can increase strength with progressive resistance exercise, which leads to decrease in low back pain.

Pelvic Stabilization During Resistance Training: Its Effect on the Development of Lumbar Extension Strength

James E. Graves, PhD, Dina C. Webb, MS, PT, Michael L. Pollock, PhD, Jan Matkozich, Scott H. Leggett, MS, David M. Carpenter, MS, Dan N. Foster, MS, Joseph Cirulli

The purpose of this study was to evaluate and compare resistance exercise training with and without pelvic stabilization on the development of isolated lumbar extension strength. Isometric torque of the isolated lumbar extensor muscles was measured at seven positions through a 72° rangeofmotion on 47 men and 30 women before and after 12 weeks of variable resistance lumbar extension training. Subjects were assigned to either a group that trained with pelvic stabilization (PSTAB, n = 21), a group that trained without pelvic stabilization (NOSTAB, n = 41), or a control group that did not train (n = 15). Subjects trained once a week with 8 to 12 repetitions to volitional exhaustion.

The PSTAB and NOSTAB groups showed significant (p 0.05) and similar increases in the weight load used for training (PSTAB = 24.1 ± 9.4 kg; NOSTAB = 19.4 ± 11.0 kg) during the 12week training period. In contrast, posttraining isometric torque values describing isolated lumbar extension strength improved only for the PSTAB group (23.5%, p 0.05) and not for the NOSTAB group (1.2%, p > 0.05) relative to controls. These data indicate that pelvic stabilization is required to effectively train the lumbar extensor muscles. The increased training load for the NOSTAB group is probably the result of exercising the muscles involved in pelvic rotation (hamstring and buttock muscles).

The Effect of Workplace Based Strengthening on Low Back Injury Rates: A Case Study in the Strip Mining Industry

Vert Mooney 1,3 Marvin Kron 2 Patrick Rummerfield 2 Bryon Holmes 1

The purpose of this study was to demonstrate the effect of a once a week exercise program focused specially at lumbar extensor strengthening. This is a comparative study where workers volunteered to exercise were compared to workers who did not exercise.
Low back claims for one year were noted to document efficacy of the training program. Change in strength was also noted. There was a 54% to 104% increase in strength during a 20 week program. The incidence of back injuries in the exercise group was .52 injuries per 200,000 employee hours versus the industry average of 1.09 back injuries per 200,000 employee hours.

The average incidence of injury for the previous nine years at the company participating in the program was 2.94 injuries per 200,000 employee hours. The injury incidence in the workers not exercising was 2.55 injuries for 200,000 employee hours.
The average workers’ compensation liability dropped from $14,430.00 per month to $380.00 per month for the study year. The significant increase in strength associated with the exercise program correlated with the greatly reduced incidence of back claims.