Fitness News You Can Use (June, 2006)

Here is the June edition of FitBits:

FitBits
Exercise ETC’s Review of Exercise Related Research
Compiled by Jeannie Patton, MS, CSCS

It’s official: Dog owners are more active, healthier

Dog ownership may be an effective intervention among adults and children for promoting physical activity. This study examined the relationship between walking, physical activity levels, and potential psychological mediators between people who owned dogs and those who did not.

A random sample of men and women aged 20 to 80 years participated. Questionnaires were mailed out in 2004 to collect information about demographics, dog ownership, leisure-time walking, physical activity levels, and theory of planned behavior (TPB).

Results of the analysis showed dog owners spent more time in mild to moderate activities and walked an average of 300 minutes a week compared to 168 minutes for non-dog owners.

The results of this analysis indicate an additional benefit to dog ownership. It appears that there is an increase in physical activity associated with the obligation to walk the dog. Fitness Professionals may be able to promote this additional exercise benefit to those who are thinking of getting a dog.

Brown, Shane. and Rhodes, Ryan. Relationships Among Dog Ownership and Leisure-Time Walking in Western Canadian Adults. Journal of Preventive Medicine. 2006; 30(2), 131-136.

###

Men and women perform squats differently, putting women’s knees at risk

It is generally accepted that female athletes exhibit different movement patterns compared to men, which increases their risk for ACL injury and patellofemoral pain. Why these differences occur is not so widely understood. Muscles of the trunk, hip and knee influence the orientation of the lower extremity during weight bearing activities. The purpose of this study was threefold: first, to compare the orientation of the lower extremity during a single leg squat among male and female athletes; second, to compare the strength of muscle groups in the trunk, hips and knees between the two genders; and third, to evaluate the association between trunk, hip and knee strength and the orientation of the knee joint during activity.

Twenty-four male and 22 female athletes served as subjects. Muscle force was measured in each subject for trunk flexion, extension and lateral flexion, hip abduction and external rotation, and knee flexion and extension. The frontal plane projection angle of the knee during a 45-degree single leg squat was also determined.

Results of the study show that men and women move in opposite directions during a single leg squat. This is consistent with other studies which show that women performing athletic moves (cross-cutting maneuvers, jump landing, etc.) tend to begin in a valgus (knock-knee) posture and move even more further into valgus, as opposed to men who begin in a valgus posture but move to more neutral alignment. This study also demonstrated that women produce less force than men in all muscle groups tested (with the exception of trunk extension.) The projection angle of the knee during the single leg squat was most closely associated with hip external rotation strength.

This is another study that documents the importance of balanced strength in the trunk, hip and knee musculature for proper knee mechanics, since women are more prone to collapse their knees inward (valgus) than men. Results of this study also indicate the importance of adequate range of motion in the hip adductors and strength in the hip external rotators. Fitness Professionals should pay close attention to strength and range of motion deficits in the trunk, hip and knee musculature and program to correct these deficits.

Willson, John, D. et al. Core strength and lower extremity alignment during single leg squats. Medicine & Science in Sports & Exercise. 2006, 38(5), 945-952.

###

Weighted walking speeds metabolism, even at slower speeds

Walking is often recommended for exercise because it is low cost, easy to do, and functional, but walking does have its limitations. Those with limitations may not be able to achieve a walking speed that would facilitate cardiorespiratory or musculoskeletal improvements, and walking may not provide enough of an overload for those with higher fitness levels. The purpose of this investigation was to determine how oxygen consumption, exercise intensity, vertical ground reaction forces and loading rate were affected while using a weighted vest during treadmill walking.

A total of ten subjects performed a standardized walking test under four weighted-vest conditions (0, 10, 15, 20% of body mass). The walking test consisted of 4-minute stages at the following speeds: 2, 2.5, 3, 3.5, and 4 miles per hour.

The results showed a significant difference in oxygen consumption in the weighted vest condition at all walking speeds. Vertical ground reaction forces increased as speed and vest mass increased. In regard to loading rate, using a weighted vest with 15 and 20% body mass showed a significant difference.

The results of this study support the use of a weighted vest to increase the metabolic cost and the dynamic loading of the skeletal system during walking and can also help Fitness Professionals determine appropriate vest mass. At lower walking speeds it may be necessary to use more weight to increase metabolic cost. At higher walking speeds a lower amount of weight will increase the metabolic cost. This study also indicated that the increases in ground reaction and loading forces were greater in all weighted vest conditions (22%) compared to the increases in metabolic cost (9%). This would indicate that wearing a weighted vest could significantly increase the mechanical stresses placed on the skeletal system without experiencing undue physiological strain.

Puthoff, Michael, L. et al. The effect of weighted vest walking on metabolic responses and ground reaction forces. Medicine & Science in Sports & Exercise. 2006, 38(4), 746-752

### 

Exercise benefits for the elderly may be more universal than expected

Many older adults are under the impression that they are too old to begin exercising and have little faith that they can improve function. These psychological barriers often affect motivation and adherence. The purpose of this study was to determine the effect of walking and resistance training on the function of older adults.

The subjects consisted of 45 women and 19 men with an average age of 83.5 years from an independent living facility. Subjects were divided into a walking group, a strength-training group, and a non-exercising control group. The subjects were supervised during training that took place twice a week for 4 months.

The participants who were in the walking and strength training groups showed significant improvements in overall body strength, flexibility, balance and agility compared to the control group. Interestingly, the results of this study showed improvements in areas that were not specifically trained. It appears that in advanced old age the benefits of exercise may be more universal and less exercise specific, since the lower the fitness level the easier it is to establish an overload. Fitness Professionals could share this research with older adults to help document that it is never too late to begin an exercise program, which may be able to both offset age- related loss of function and preserve function longer.

Simons, Robert and Andel, Ross. The Effects of Resistance Training and Walking on Functional Fitness in Advanced Old Age. The Journal of Aging and Health. 2006; 18(1), 56-69.