Catherine Crofts

Women-only mass participation sporting events: does participation facilitate changes in physical activity?

Abstract There is little evidence supporting the claim that mass participation sporting events (MPSE) increase the populations physical activity (PA). This research aimed to identify the demographic, motivational and PA profile of participants in a women-only non-elite triathlon race series. It also aimed to identify whether PA in previously insufficiently active participants increased before the event, and remained elevated three months after the event. Participants were surveyed before (n=452) and three months after their event (n=95). The results showed that the participants were predominantly sufficiently active prior to the event. Although PA levels decreased post-event, they remained predominantly sufficient. Nearly 50% of the inactive women pre-event remained sufficiently active three months after their event. Challenge and competition were key motivators for participation. MPSEs facilitate previously inactive women into sufficient levels of PA. Further research should explore their capacity to facilitate long-term maintenance of PA.

Identifying hyperinsulinaemia in the absence of impaired glucose tolerance: An examination of the Kraft database

OBJECTIVE Hyperinsulinaemia is associated with development of chronic metabolic disease and is emerging as a health risk independent to that of insulin resistance. However, little is known to what extent hyperinsulinaemia occurs with normal glucose tolerance in lean subjects. METHOD Oral glucose tolerance tests with concurrent insulin assay were conducted during the 1970s-1990s. Participants were classified according to glucose tolerance and insulin response pattern. Analysis of variance compared differences in plasma glucose, plasma insulin, and demographic and metabolic risk factors between groups. RESULTS Participants with normal glucose tolerance comprised 54% (n=4185) of the total cohort. Of these, just over half (n=2079) showed hyperinsulinaemia despite normal glucose clearance. Obesity had a modest association with hyperinsulinaemia in people with normal glucose tolerance. Fasting insulin had limited value in diagnosing hyperinsulinaemia. The majority of participants (93%) with impaired glucose tolerance or diabetes had concurrent hyperinsulinaemia. CONCLUSION Hyperinsulinaemia in the absence of impaired glucose tolerance may provide the earliest detection for metabolic disease risk and likely occurs in a substantial proportion of an otherwise healthy population. Dynamic insulin patterning may produce more meaningful and potentially helpful diagnoses. Further research is needed to investigate clinically useful hyperinsulinaemia screening tools.

Can insulin response patterns predict metabolic disease risk in individuals with normal glucose tolerance

To the Editor: We commend the authors of the recent publication in Diabetologia entitled ‘Glucose patterns during an oral glucose tolerance test and associations with future diabetes, cardiovascular disease and all-cause mortality rate’ [1] and would encourage them to repeat their investigation using insulin response patterns in people with normal glucose tolerance. Hyperinsulinaemia is becoming well-established in the aetiology of many metabolic diseases [2], yet many people will be unaware that they are at risk. Insulin levels are posited to be elevated for many years, possibly even decades, before changes in blood glucose are noted [3, 4]. Although fasting insulin is used inmany studies as a disease riskmarker, it has a high coefficient of variation leading to concerns about repeatability [5]. There has been little emphasis on the use of insulin response patterns to assess the risk of metabolic disease, yet the patterns observed when tracking blood insulin levels following an OGTT may provide an earlier opportunity to assess disease risk compared with changes in blood glucose levels. Hayashi and colleagues noted that cumulative incidence of type 2 diabetes in Japanese-American men over 10 years of follow-up was between 38% and 48% in those who reached a peak insulin level at 120 min following a 75 g OGTT, which was higher than those whose insulin levels peaked at 30 or 60 min (cumulative incidence, <16%) [6]. However, these response patterns were based on relative insulin serum levels in a cohort that included a high proportion of participants with pre-existing impaired fasting glucose and/or impaired glucose tolerance [5]. Between 1970 and 1990, Dr J. R. Kraft collated a large database holding data from multiple-sampled OGTTs with insulin assays. Further analysis of this database suggests that up to 75% of people with normal glucose tolerance may have hyperinsulinaemia [7], but there are no longitudinal outcomes to support risk calculations. There is a distinct paucity of data on insulin response patterns and subsequent risk of cardiovascular disease and we believe the authors would advance the field with further data analysis.

Post-event behavioural intentions of participants in a women-only mass participation sporting event

Little is known about the long-term physical activity (PA) behaviours of women after participating in a non-elite mass participation sporting event (MPSE). Three months post-event, 95 women reported their intentions to participate in: 1) the same event the following year; 2) other triathlons and/or other MPSE. The results suggest a strong association between the psychological connection model (PCM) and behavioural intentions. Most women with low intentions to repeat the event were in attraction while most women with high intentions to return were in attachment. These results show that, in addition, to providing short-term inducement for increased PA, short-distance MPSEs have the potential to act as ‘gateway’ events for other MPSE.