Associations between grip strength and incident type 2 diabetes: findings from the UK Biobank prospective cohort study.

INTRODUCTION: Grip strength has been associated with chronic diseases and mortality. However, current evidence of the association between grip strength and incident type 2 diabetes mellitus (T2DM) is controversial. The aim of this study was to investigate the associations of absolute and relative grip strength with incident T2DM and whether these associations differ by sociodemographic, lifestyle and adiposity-related factors. RESEARCH DESIGN AND METHODS: This was a prospective cohort study of 166 894 participants in the UK Biobank (mean age 56.5 years, 54.4% women). The outcome was T2DM incidence and the exposure was grip strength, expressed in absolute (kg) and relative (kg per kg of body weight) values. The association between grip strength and T2DM incidence was investigated using Cox-proportional regression. RESULTS: The median follow-up was 5.3 years (IQR: 4.7-6.1). During this time, 3713 participants developed T2DM. Lower grip strength was associated with a higher risk of T2DM in both sexes. Those in the lowest quintile of absolute grip strength had a 50% higher risk in men (HR: 1.50 (95% CI: 1.30 to 1.73)) and 25% higher risk in women (HR: 1.25 (95% CI: 1.06 to 1.47)) compared with those in the highest quintile. For relative grip strength, risk of diabetes was more than double for men (HR: 2.22 (95% CI: 1.84 to 2.67)) and 96% higher for women (HR: 1.96 (95% CI: 1.52 to 2.53)) in the lowest compared with highest quintiles. CONCLUSIONS: Grip strength is associated with a higher risk of T2DM incidence in both men and women independent of important confounding factors including age, deprivation, adiposity and lifestyle. However, the associations were stronger when grip strength is expressed relative to body weight, which could reflect the importance of muscle quality.

Ethnic differences in prevalence of actionable HbA1c levels in UK Biobank: implications for screening.

INTRODUCTION: Early detection and treatment of diabetes as well as its prevention help lessen longer-term complications. We determined the prevalence of pre-diabetes and undiagnosed diabetes in the UK Biobank and standardized the results to the UK general population. RESEARCH DESIGN AND METHODS: This cross-sectional study analyzed baseline UK Biobank data on plasma glycated hemoglobin (HbA1c) to compare the prevalence of pre-diabetes and undiagnosed diabetes mellitus in white, South Asian, black, and Chinese participants. The overall and ethnic-specific results were standardized to the UK general population aged 40-70 years of age. RESULTS: Within the UK Biobank, the overall crude prevalence was 3.6% for pre-diabetes, 0.8% for undiagnosed diabetes, and 4.4% for either. Following standardization to the UK general population, the results were similar at 3.8%, 0.8%, and 4.7%, respectively. Crude prevalence was much higher in South Asian (11.0% pre-diabetes; 3.6% undiagnosed diabetes; 14.6% either) or black (13.8% pre-diabetes; 3.0% undiagnosed diabetes; 16.8% either) participants. Only six middle-aged or old-aged South Asian individuals or seven black would need to be tested to identify an HbA1c result that merits action. CONCLUSIONS: Single-stage population screening for pre-diabetes or undiagnosed diabetes in middle-old or old-aged South Asian and black individuals using HbA1c could be efficient and should be considered.

Dose-response associations of cardiorespiratory fitness with all-cause mortality and incidence and mortality of cancer and cardiovascular and respiratory diseases: the UK Biobank cohort study.

OBJECTIVE: To investigate the association of cardiorespiratory fitness with all-cause mortality, and cardiovascular disease (CVD), respiratory disease, chronic obstructive pulmonary disease (COPD) and cancer mortality and incidence. DESIGN: Prospective population-based study. SETTING: UK Biobank. PARTICIPANTS: Of the 5 02 628 (5.5% response rate) participants recruited by UK Biobank, we included 73 259 (14.6%) participants with available data in this analysis. Of these, 1374 participants died and 4210 developed circulatory diseases, 1293 respiratory diseases and 4281 cancer, over a median of 5.0 years (IQR 4.3-5.7) follow-up. MAIN OUTCOME MEASURES: All-cause mortality and circulatory disease, respiratory disease, COPD and cancer (such as colorectal, lung, breast and prostate) mortality/incidence. Fitness was estimated using a submaximal cycle ergometer test. RESULTS: The HR for all-cause mortality for each metabolic equivalent of task (MET) higher fitness was 0.96 (95% CI 0.93 to 0.98). Similar results were observed for incident circulatory disease (HR 0.96 [0.95 to 0.97]), respiratory disease (HR 0.96 [0.94 to 0.98]), COPD (HR 0.90 [0.86 to 0.95) and colorectal cancer (HR 0.96 [0.92 to 1.00]). Nonlinear analysis revealed that a high level of fitness (>10METs) was associated with a greater incidence of atrial fibrillation (HR 1.24 [1.07 to 1.44]) and prostate cancer (HR 1.16 [1.02 to 1.32]) compared with average fitness. All results were adjusted for sociodemographic, lifestyle and dietary factors, body composition, and morbidity at baseline and excluded events in the first 2 years of follow-up. CONCLUSIONS: Higher cardiorespiratory fitness was associated with lower risk of premature mortality and incidence of CVD, respiratory disease and colorectal cancer.

Contribution of type 2 diabetes to all-cause mortality, cardiovascular disease incidence and cancer incidence in white Europeans and South Asians: findings from the UK Biobank population-based cohort study.

Objective: To investigate whether the health implications of having type 2 diabetes (T2D) were different in South Asian compared with white European participants. Research design and methods: Prospective data from UK Biobank were used, and 457 935 participants of white European and 7102 of South Asian background were included. Cox proportional regression was performed to investigate the association between T2D and health outcome by ethnicity. Results: Over a mean of 7.0 years (IQR 6.3-7.6) of follow-up, 12 974 participants had died, and 30 347 and 27 159 developed cardiovascular disease (CVD) and cancer, respectively. South Asians had a higher risk for CVD mortality (HR: 1.42, 95% CI 1.07 to 1.89) and incidence (HR: 1.78, 95% CI 1.63 to 1.94), but a decreased risk for cancer mortality (HR: 0.59, 95% CI 0.41 to 0.85) and incidence (HR: 0.80, 95% CI 0.70 to 0.92) compared with white Europeans. Compared with individuals without T2D, both white Europeans and South Asians with T2D had a higher risk for all-cause mortality (1.59 (1.48 to 1.71) vs 2.83 (1.76 to 4.53)), CVD mortality (2.04 (1.82 to 2.28) vs 4.40 (2.37 to 8.16)) and CVD incidence (1.37 (1.31 to 1.44) vs 1.60 (1.31 to 1.95)), respectively. However, the magnitude of the risk was higher for South Asians than white Europeans. Conclusions: Although T2D was associated with a higher risk for all-cause mortality and CVD incidence and mortality, in both white Europeans and South Asians, the risk experienced by South Asians with T2D was higher than their white European counterparts.

Sex differences in the response to resistance exercise training in older people.

Resistance exercise training is known to be effective in increasing muscle mass in older people. Acute measurement of protein metabolism data has indicated that the magnitude of response may differ between sexes. We compared adaptive responses in muscle mass and function to 18 weeks resistance exercise training in a cohort of older (>65 years) men and women. Resistance exercise training improved knee extensor maximal torque, 4 m walk time, time to complete five chair rises, muscle anatomical cross-sectional area (ACSA) and muscle quality with no effect on muscle fat/water ratio or plasma glucose, insulin, triacylglycerol, IL-6, and TNF-α Differences between sexes were observed for knee extensor maximal torque and muscle quality with greater increases observed in men versus women (P < 0.05). Maximal torque increased by 15.8 ± 10.6% in women and 41.7 ± 25.5% in men, whereas muscle quality increased by 8.8 ± 17.5% in women and by 33.7 ± 25.6% in men. In conclusion, this study has demonstrated a difference in the magnitude of adaptation, of some of the outcome measures employed, in response to 18 weeks of resistance exercise training between men and women. The mechanisms underlying this observation remain to be established.

The Effect of Krill Oil Supplementation on Exercise Performance and Markers of Immune Function.

BACKGROUND: Krill oil is a rich source of the long-chain n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which may alter immune function after exercise. The aim of the study was to determine the effects of krill oil supplementation on post exercise immune function and performance. METHODS: Nineteen males and 18 females (age: 25.8 ± 5.3 years; mean ± S.D.) were randomly assigned to 2 g/day of krill oil (n = 18) or placebo (n = 19) supplementation for 6 weeks. A maximal incremental exercise test and cycling time trial (time to complete set amount of work) were performed pre-supplementation with the time trial repeated post-supplementation. Blood samples collected pre- and post- supplementation at rest, and immediately, 1 and 3h post-exercise. Plasma IL-6 and thiobarbituric acid reactive substances (TBARS) concentrations and, erythrocyte fatty acid composition were measured. Natural killer (NK) cell cytotoxic activity and peripheral blood mononuclear cell (PBMC) IL-2, IL-4, IL-10, IL-17 and IFNγ production were also measured. RESULTS: No effects of gender were noted for any variable. PBMC IL-2 and NK cell cytotoxic activity were greater (P < 0.05) 3h post exercise in the krill oil compared to the control group. Plasma IL-6 and TBARS, PBMC IL-4, IL-10, IL-17 and IFNγ production, along with performance and physiological measures during exercise, were not different between groups. CONCLUSION: Six weeks of krill oil supplementation can increase PBMC IL-2 production and NK cell cytotoxic activity 3h post-exercise in both healthy young males and females. Krill oil does not modify exercise performance.

The effect of short-duration sprint interval exercise on plasma postprandial triacylglycerol levels in young men.

It is well established that regular exercise can reduce the risk of cardiovascular disease, although the most time-efficient exercise protocol to confer benefits has yet to be established. The aim of the current study was to determine the effects of short-duration sprint interval exercise on postprandial triacylglycerol. Fifteen healthy male participants completed two 2 day trials. On day 1, participants rested (control) or carried out twenty 6 s sprints, interspersed with 24 s recovery (sprint interval exercise--14 min for total exercise session). On day 2, participants consumed a high-fat meal for breakfast with blood samples collected at baseline, 2 h and 4 h. Gas exchange was also measured at these time points. On day 2 of control and sprint interval exercise trials, there were no differences (P < 0.05) between trials in plasma glucose, triacylglycerol, insulin or respiratory exchange ratio (RER). The area under the curve for plasma triacylglycerol was 7.67 ± 2.37 mmol · l(-1) x 4 h(-1) in the control trial and 7.26 ± 2.49 mmol · l(-1) x 4 h(-1) in the sprint interval exercise trial. Although the sprint exercise protocol employed had no significant effect on postprandial triacylglycerol, there was a clear variability in responses that warrants further investigation.

The effect of high intensity interval exercise on postprandial triacylglycerol and leukocyte activation--monitored for 48 h post exercise.

Postprandial phenomenon are thought to contribute to atherogenesis alongside activation of the immune system. A single bout of high intensity interval exercise attenuates postprandial triacylglycerol (TG), although the longevity and mechanisms underlying this observation are unknown. The aims of this study were to determine whether this attenuation in postprandial TG remained 2 days after high intensity interval exercise, to monitor markers of leukocyte activation and investigate the underlying mechanisms. Eight young men each completed two three day trials. On day 1: subjects rested (Control) or performed 5 x 30 s maximal sprints (high intensity interval exercise). On day 2 and 3 subjects consumed high fat meals for breakfast and 3 h later for lunch. Blood samples were taken at various times and analysed for TG, glucose and TG-rich lipoprotein (TRL)-bound LPL-dependent TRL-TG hydrolysis (LTTH). Flow cytometry was used to evaluate granulocyte, monocyte and lymphocyte CD11b and CD36 expression. On day 2 after high intensity interval exercise TG area under the curve was lower (P<0.05) (7.46 ± 1.53 mmol/l/7h) compared to the control trial (9.47 ± 3 .04 mmol/l/7h) with no differences during day 3 of the trial. LTTH activity was higher (P<0.05) after high intensity interval exercise, at 2 hours of day 2, compared to control. Granulocyte, monocyte and lymphocyte CD11b expression increased with time over day 2 and 3 of the study (P<0.0001). Lymphocyte and monocyte CD36 expression decreased with time over day 2 and 3 (P<0.05). There were no differences between trials in CD11b and CD36 expression on any leukocytes. A single session of high intensity interval exercise attenuated postprandial TG on day 2 of the study, with this effect abolished by day 3.The reduction in postprandial TG was associated with an increase in LTTH. High intensity interval exercise had no effect on postprandial responses of CD11b or CD36.

The effect of exercise induced cytokines on insulin stimulated glucose transport in C2C12 cells.

Skeletal muscle contractile activity increases the production of the myokines interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-15 (IL-15) and also skeletal muscle glucose transport. Previous work has revealed a role for IL-6 in mediating glucose uptake, while research on the physiological roles of IL-8 and IL-15 is not so abundant. In the present study we investigated the effects of different concentrations and combinations of IL-6, IL-8 and IL-15 on insulin stimulated glucose transport in C2C12 cells. Furthermore, we also measured AMPK Thr172 and Akt Ser473 phosphorylation via Western blotting. Exposure to 20 pg/ml of individual cytokines had no affect on glucose transport while 1 ng/ml enhanced (P<0.05) glucose uptake with IL-6, IL-8 and IL-15, respectively. Moreover, the combinations of IL-8+IL-6 and IL-15+IL-6 at both 20 pg/ml and 1 ng/ml stimulated (P<0.05) glucose transport with IL-8+IL-15 and IL-8+IL-6+IL-15 only increasing (P<0.05) glucose transport at 1 ng/ml, with no affect observed of these combinations at 20 pg/ml. The changes in glucose transport were all associated with an increase (P<0.05) in AMPK Thr172 phosphorylation with no changes in Akt Ser473 phosphorylation. These findings demonstrated that the exercise induced myokines IL-6, IL-8 and IL-15 enhance glucose transport at 1 ng/ml, with changes only seen at 20 pg/ml with certain myokine combinations. Furthermore these changes in insulin stimulated glucose transport were associated with increased AMPK phosphorylation.