It's unusual for any study to have large numbers of participants, yet this study from the US and Canada involved nearly 73000 sedentary women. The women volunteered to participate in a 30 day challenge and results were collated to determine the effectiveness of this initial 30 day exercise program. Supported by Curves International, and using the Curves staff and equipment this study shows significant results over this 30 day period. There are however a few issues I have with this research process.
Firstly, participants filled in pre-exercise and food diaries online, meaning it was difficult for researchers to clarify or quantify answers outside those completed by the participant. Collection of baseline anthrop data was performed by Curves staff who in many cases are not qualified or trained to take such measures meaning the level of accuracy must be questioned. Given this level of accuracy the small changes recorded as mean values must also be questioned. Weight loss change of -1.1%, body fat of -1.9%, total centimeters of -1.5%, and BMI down by -1.5%, means generally all scores changed by less than 2%. Such a small change might be expected over a 30 day period, but such a small value means the accuracy of initial and post measures needs to be quite accurate in order to validate such changes. On one hand, the saving grace here is that these changes occurred across such a large number of participants, but the downside is that there is value in Curves staff and programs showing that such changes are successful and the researchers were not on hand to determine correct measures and scoring for such a large number of subjects.
For me the most impressive results from this study was the resultant changes in lifestyle related behaviours. Reductions in alcohol, fat, and sugar as well as increases in fibre and calcium shows that an individual can make significant changes in a short amount of time and this value cannot be understated.
The full abstract is included below........
Numerous studies have documented the value of exercise in controlled clinical trials. However, few large scale studies have evaluated the effects of initiation of resistance-training programs.
PURPOSE: To evaluate the impact of a 30-day international fitness intervention on fitness and health behaviors in a large-scale population. METHODS: 72,870 sedentary women (44.0 +/- 13 yrs, 83.3 +/- 19.7 kg, 31.9 +/- 7 kg/m2 BMI, 37.9 +/- 7% fat) responding to advertisements for a 30-day fitness challenge at Curves(R) clubs in the United States and Canada volunteered to participate in this study. Subjects gave online consent and then completed exercise, food frequency, and physical activity-related questionnaires. In addition, baseline body composition, obtained using a handheld bioelectrical impedance analyzer (BIA), blood pressure, and circumference measurements were taken by trained personnel. Participants followed the Curves 30-min circuit training program 3 d/wk. Each circuit-style workout consisted of 14 hydraulic resistance-exercises that targeted opposing muscle groups in a concentric-only fashion. Subjects performed the resistance-exercise for 30-sec followed by performing floor-based callisthenic (e.g. walking/skipping in place, arm circles, etc.) exercises for a 30-sec time period in an effort to maintain heart rate between 60% and 85% of age-predicted maximum heart rate. Participants were also encouraged to walk on non-training days and make positive changes in their diet. After 4-wks, subjects repeated questionnaires and had post-measurements recorded. Data were analyzed by dependent T-tests and are presented as mean +/- SD changes from baseline.
RESULTS: Post-study results were obtained on 34,677 participants. Participants experienced significant (p < 0.05) decreases in body weight (-0.86 +/- 2.2 kg, -1.1%; n = 34,667), percent fat (-0.7 +/- 2.5%, -1.9%; n = 34,349), total centimeters (-7.62 +/- 17.78 cm, -1.5%; n = 33,899), BMI (-0.47 +/- 2.7 kg/m2, -1.5%; n = 12,167), systolic BP (-2.6 +/- 12.5 mm Hg, -2.1%; n = 11,767), and diastolic BP (-2.3 +/- 9.0 mm Hg, -2.9%; n = 11,711), as well as an increase in fat-free weight (0.05kg +/- 2.4 kg, 0.1%; n = 34,312). Participants also reported significantly less (p<0.05) weekly (-10%) and monthly (-17%) alcohol consumption, sugar intake (-24%), and fat intake (-22%) with greater calcium intake (5.3%), and fiber intake (6.8%).
CONCLUSIONS: Significant improvements in body composition, markers of health, and positive health behaviors can be achieved through short-term circuit training fitness initiatives.
PRACTICAL APPLICATIONS: Short-term circuit-training programs can be effectively used to promote positive changes in fitness and attitudes about health.
ACKNOWLEDGMENTS: This study was supported by Curves International, Waco TX and Avon Inc., New York NY.