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Abstract
Background: Exercise training improves performance and biochemical parameters on average, but wide interindividual variability exists, with individuals classified as responders (R) or non-responders (NRs), especially between populations with higher or lower levels of insulin resistance. This study assessed the effects of high-intensity interval training (HIIT) and the prevalence of NRs in adult women with higher and lower levels of insulin resistance.Methods: Forty adult women were assigned to a HIIT program, and after training were analyzed in two groups; a group with higher insulin resistance (H-IR, 40 ± 6 years; BMI: 29.5 ± 3.7 kg/m2; n = 20) and a group with lower insulin resistance (L-IR, 35 ± 9 years; 27.8 ± 2.8 kg/m2; n = 20). Anthropometric, cardiovascular, metabolic, and performance variables were measured at baseline and after 10 weeks of training.Results: There were significant training-induced changes [delta percent (Δ%)] in fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) scores in the H-IR group (−8.8, −26.5, −32.1%, p < 0.0001), whereas no significant changes were observed in the L-IR. Both groups showed significant pre-post changes in other anthropometric variables [waist circumference (−5.2, p < 0.010, and −3.8%, p = 0.046) and tricipital (−13.3, p < 0.010, and −13.6%, p < 0.0001), supra-iliac (−19.4, p < 0.0001, and −13.6%, p < 0.0001), and abdominal (−18.2, p < 0.0001, and −15.6%, p < 0.010) skinfold measurements]. Systolic blood pressure decreased significantly only in the L-IR group (−3.2%, p < 0.010). Both groups showed significant increases in 1RMLE (+12.9, p < 0.010, and +14.7%, p = 0.045). There were significant differences in the prevalence of NRs between the H-IR and L-IR groups for fasting glucose (25 vs. 95%, p < 0.0001) and fasting insulin (p = 0.025) but not for HOMA-IR (25 vs. 45%, p = 0.185).Conclusion: Independent of the “magnitude” of the cardiometabolic disease (i.e., higher vs. lower insulin resistance), no differences were observed in the NRs prevalence with regard to improved HOMA-IR or to anthropometric, cardiovascular, and muscle performance co-variables after 10 weeks of HIIT in sedentary adult women. This research demonstrates the protective effect of HIIT against cardiometabolic disease progression in a sedentary population.
Highlights
Exercise training is a strategy for the prevention and treatment of several inactivity-related metabolic diseases, such as insulin resistance (Álvarez et al, 2014) and type 2 diabetes mellitus (T2DM) (Alvarez et al, 2016)
There were significant (p ≤ 0.05) pre-post changes in one repetition maximum test of leg extension (1RMLE) in the higher insulin resistance group (H-IR) (+12.9) and lower insulin resistance group (L-IR) (+14.7%) groups (Table 2), whereas one repetition maximum test of upper row (1RMUR) remained unchanged in both groups
The major findings of this study indicate that (i) high-intensity interval training (HIIT) promotes significantly more benefits in training-induced changes in fasting glucose, fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) scores in adult women with higher insulin resistance; (ii) the NRs prevalence was significantly different between the H-IR vs. L-IR groups with regard to improve fasting glucose and fasting insulin but not for HOMA-IR scores; and (iii) both the H-IR and L-IR groups experienced similar positive training-induced changes and similar NRs prevalence with regard to anthropometric, cardiovascular, and muscle strength performance (1RMLE, 1RMUR) measures
Summary
Exercise training is a strategy for the prevention and treatment of several inactivity-related metabolic diseases, such as insulin resistance (Álvarez et al, 2014) and type 2 diabetes mellitus (T2DM) (Alvarez et al, 2016). Some subjects, termed responders (R), achieve benefits after training, while others, termed non-responders (NRs), show an unchanged or worsened response (Bouchard et al, 2012; Bonafiglia et al, 2016; Álvarez et al, 2017) In the literature, this phenomenon has been characterized using several terms, such as low/high responders (Davidsen et al, 2011), non-responders/responders (Sisson et al, 2009), or as an adverse response (Bouchard et al, 2012); in these studies, similar but slightly different methodological criteria have been applied for identifying R and NRs. Genetic (Stephens et al, 2015) and environmental factors (Bouchard and Rankinen, 2001) have been suggested to be responsible for this variability, not all of Abbreviations: T2DM, type 2 diabetes mellitus; R, responders; NRs, nonresponders: HIIT, high-intensity interval training; H-IR: higher insulin resistance group; L-IR, lower insulin resistance group; BMI, body mass index; HOMAIR, homeostasis model assessment of insulin resistance; 1RM, one repetition maximum strength test; 1RMLE, one repetition maximum test of leg extension; 1RMUR, one repetition maximum test of upper row; HbA1c, glycated hemoglobin, OGTT, oral glucose tolerance test; VO2peak, maximum peak of oxygen uptake, VO2max, maximum oxygen uptake. This study assessed the effects of high-intensity interval training (HIIT) and the prevalence of NRs in adult women with higher and lower levels of insulin resistance
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