Muscle-strengthening and conditioning activities and risk of type 2 diabetes: a prospective study in two cohorts of US women.
BACKGROUND
It is well established that aerobic physical activity can lower the risk of type 2 diabetes (T2D), but whether muscle-strengthening activities are beneficial for the prevention of T2D is unclear. This study examined the association of muscle-strengthening activities with the risk of T2D in women.


RESULTS
We prospectively followed up 99,316 middle-aged and older women for 8 years from the Nurses' Health Study ([NHS] aged 53-81 years, 2000-2008) and Nurses' Health Study II ([NHSII] aged 36-55 years, 2001-2009), who were free of diabetes, cancer, and cardiovascular diseases at baseline. Participants reported weekly time spent on resistance exercise, lower intensity muscular conditioning exercises (yoga, stretching, toning), and aerobic moderate and vigorous physical activity (MVPA) at baseline and in 2004/2005. Cox regression with adjustment for major determinants for T2D was carried out to examine the influence of these types of activities on T2D risk. During 705,869 person years of follow-up, 3,491 incident T2D cases were documented. In multivariable adjusted models including aerobic MVPA, the pooled relative risk (RR) for T2D for women performing 1-29, 30-59, 60-150, and >150 min/week of total muscle-strengthening and conditioning activities was 0.83, 0.93, 0.75, and 0.60 compared to women reporting no muscle-strengthening and conditioning activities (p<0.001 for trend). Furthermore, resistance exercise and lower intensity muscular conditioning exercises were each independently associated with lower risk of T2D in pooled analyses. Women who engaged in at least 150 min/week of aerobic MVPA and at least 60 min/week of muscle-strengthening activities had substantial risk reduction compared with inactive women (pooled RR = 0.33 [95% CI 0.29-0.38]). Limitations to the study include that muscle-strengthening and conditioning activity and other types of physical activity were assessed by a self-administered questionnaire and that the study population consisted of registered nurses with mostly European ancestry.


CONCLUSIONS
Our study suggests that engagement in muscle-strengthening and conditioning activities (resistance exercise, yoga, stretching, toning) is associated with a lower risk of T2D. Engagement in both aerobic MVPA and muscle-strengthening type activity is associated with a substantial reduction in the risk of T2D in middle-aged and older women.
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America ; Department of Sport Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology and Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark.
Anders
A
Grøntved
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America ; Saw Swee Hock School of Public Health and Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore, Republic of Singapore.
An
A
Pan
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America ; Department of Pharmaceutical Sciences, Massachusetts College of Pharmacy and Health Sciences University, Boston, Massachusetts, United States of America.
Rania A
RA
Mekary
Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts, United States of America ; Channing Division of Network Medicine, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts, United States of America.
Meir
M
Stampfer
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America ; Channing Division of Network Medicine, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts, United States of America ; Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America.
Walter C
WC
Willett
Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts, United States of America ; Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America.
JoAnn E
JE
Manson
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, United States of America ; Channing Division of Network Medicine, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts, United States of America ; Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America.
Frank B
FB
Hu
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology* / Q000209:etiology; D015444:Exercise; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D053580:Muscle Strength; D064797:Physical Conditioning, Human; D011446:Prospective Studies; D012307:Risk Factors; D057566:Self Report; D014481:United States / Q000453:epidemiology