In the Journals

Lactate levels higher, heart rate lower after exercise in women with type 2 diabetes

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October 6, 2015

Older women with type 2 diabetes exerted greater effort to complete a series of low- to moderate-intensity exercises than their matched controls who did not have type 2 diabetes, according to research in BMJ Open Diabetes Research & Care.

In a cross-sectional study of women with overweight who did and did not have type 2 diabetes, researchers found both heart rate and plasma lactate concentrations to be significant predictors of a participant’s rating of perceived exertion during exercise, with women with type 2 diabetes having a higher plasma lactate concentration and lower peak oxygen consumption.

“Taken together, these measures suggest that women with [type 2 diabetes] experience exercise, even at relatively low levels, to be more strenuous than their counterparts without diabetes,” Amy G. Huebschmann, MD, of the department of internal medicine at University of Colorado School of Medicine, and colleagues wrote. “Exercise effort is an important barrier to physical activity because it is modifiable and the perception of more intense effort during exercise has been associated with lower levels of usual physical activity.”

Amy Huebschmann

Amy G. Huebschmann

Huebschmann and colleagues analyzed data from 54 postmenopausal women aged 50 to 75 years with and without type 2 diabetes (mean age, 59 years; mean BMI, 30 kg/m²). Within the cohort, 26 women had type 2 diabetes for an average duration of 5.1 years. Women with prolonged type 2 diabetes (> 20 years) or poor diabetes control (HbA1c > 8.5%) were excluded from the study.

Women in the cohort completed eight bouts of submaximal, constant-load, cycle ergometer exercise with work rates alternating between 30 W and 35% of individually measured peak oxygen consumption (35% VO peak). Each exercise bout was 8 minutes; participants and research staff were masked to the work rate to minimize bias. Participants self-reported rating of perceived exertion. Scores range from 6 to 20; an 11 is considered “light,” whereas a 13 is considered “somewhat hard.” Researchers also measured plasma lactate concentration, heart rate, VO peak, glucose levels, pulse-wave velocity and homeostasis model assessment of insulin resistance (HOMA-IR).

Researchers found that VO peak was lower in women with type 2 diabetes compared with controls (P = .003). Rating of perceived exertion was not greater in the women with type 2 diabetes, although plasma lactate measurements were greater (P = .004 at 30 W; P < .05 at 35% VO peak).

Researchers also found that women with higher lactate levels, higher heart rate and hypertension had a greater rating of perceived exertion (P < .05), a result researchers called surprising.

“This finding warrants confirmation in future studies to ensure that it is not spurious,” the researchers wrote. Researchers did not find an association between glucose levels and rating of perceived exertion.

“Our effort measures were obtained at work rates that are less intense than many activities of daily living,” Huebschmann told Endocrine Today. “Because people tend to prefer physical activities with an intensity in the 11 to 14 range, our findings provide some additional support to existing concerns that overweight, sedentary individuals with and without [type 2 diabetes] may avoid activities of daily living because they are perceptually too difficult and hence unpleasant.” by Regina Schaffer

Disclosure: The researchers report no relevant financial disclosures.