Dr Emma Cockcroft
Associate Research Fellow

Key publications | Publications by category | Publications by year

Key publications



Cockcroft EJ, williams C, jackman S, armstrong N, barker A (In Press). Agreement and Reliability of Fasted and Oral Glucose Tolerance Test-Derived Indices of Insulin Sensitivity and Beta Cell Function in Boys. International Journal of Sports Medicince. Full text
Cockcroft EJ, Williams CA, Jackman SR, Bassi S, Armstrong N, Barker AR (2018). A single bout of high-intensity interval exercise and work-matched moderate-intensity exercise has minimal effect on glucose tolerance and insulin sensitivity in 7- to 10-year-old boys. Journal of Sports Sciences, 36(2), 149-155.

Abstract:
A single bout of high-intensity interval exercise and work-matched moderate-intensity exercise has minimal effect on glucose tolerance and insulin sensitivity in 7- to 10-year-old boys

(C) 2017 Informa UK Limited, trading as Taylor. and. Francis Group. The purpose of this study was to assess the acute effect of high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE) on glucose tolerance, insulin sensitivity and fat oxidation in young boys. Eleven boys (8.8 ± 0.8 y) completed three conditions: 1) HIIE; 2) work-matched MIE; and 3) rest (CON) followed by an oral glucose tolerance test (OGTT) to determine glucose tolerance and insulin sensitivity (Cederholm index). Fat oxidation was measured following the OGTT using indirect calorimetry. There was no effect for condition on plasma [glucose] and [insulin] area under the curve (AUC) responses following the OGTT (P andgt; 0.09). However, there was a "trend" for a condition effect for insulin sensitivity with a small increase after HIIE (P  0.04, ES  0.28, 9.7%) and MIE (P  0.07, ES  0.21, 6.5%) compared to CON. There was an increase in fat oxidation AUC following HIIE (P  0.008, ES  0.79, 38.9%) compared to CON, but with no differences between MIE and CON and HIIE and MIE (P andgt; 0.13). In conclusion, 7- to 10-year-old boys may have limited scope to improve insulin sensitivity and glucose tolerance after a single bout of HIIE and MIE. However, fat oxidation is augmented after HIIE but not MIE.
 Abstract. Full text
Liabo K, Boddy K, Burchmore H, Cockcroft E, Britten N (2018). Clarifying the roles of patients in research. Bmj, 361Author URL
Jackman SR, Brook MS, Pulsford RM, Cockcroft EJ, Campbell MI, Rankin D, Atherton P, Smith K, Bowtell JL (2018). Tart cherry concentrate does not enhance muscle protein synthesis response to exercise and protein in healthy older men. Exp Gerontol, 110, 202-208.

Abstract:
Tart cherry concentrate does not enhance muscle protein synthesis response to exercise and protein in healthy older men.

BACKGROUND: Oxidative stress and inflammation may contribute to anabolic resistance in response to protein and exercise in older adults. We investigated whether consumption of montmorency cherry concentrate (MCC) increased anabolic sensitivity to protein ingestion and resistance exercise in healthy older men. METHODS: Sixteen healthy older men were randomized to receive MCC (60 mL·d-1) or placebo (PLA) for two weeks, after baseline measures in week 1. During week 3, participants consumed 10 g whey protein·d-1 and completed three bouts of unilateral leg resistance exercise (4 × 8-10 repetitions at 80% 1RM). Participants consumed a bolus (150 mL) and weekly (50 mL) doses of deuterated water. Body water 2H enrichment was measured in saliva and vastus lateralis biopsies were taken from the non-exercised leg after weeks 1, 2 and 3, and the exercised leg after week 3, to measure tracer incorporation at rest, in response to protein and protein + exercise. RESULTS: Myofibrillar protein synthesis increased in response to exercise + protein compared to rest (p andlt; 0.05) in both groups, but there was no added effect of supplement (MCC: 1.79 ± 0.75 EX vs 1.15 ± 0.40 rest; PLA: 2.22 ± 0.54 vs 1.21 ± 0.18; all %·d-1). Muscle total NFĸB protein was decreased with exercise and protein in MCC (NFĸB: -20.7 ± 17.5%) but increased in PLA (NFĸB: 17.8 ± 31.3%, p  0.073). CONCLUSION: Short-term MCC ingestion does not affect the anabolic response to protein and exercise in healthy, relatively active, older men, despite MCC ingestion attenuating expression of proteins involved in the muscle inflammatory response to exercise, which may influence the chronic training response.
 Abstract.  Author URL Full text
Cockcroft EJ, Williams CA, Weaver H, O‘Connor A, Jackman SR, Armstrong N, Barker AR (2017). Acute Exercise and Insulin Sensitivity in Boys: a Time-Course Study. Int J Sports Med, 38(13), 967-974.

Abstract:
Acute Exercise and Insulin Sensitivity in Boys: a Time-Course Study.

This study examined the time course of adaptions in insulin sensitivity (IS) in adolescent boys after acute high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE). Eight boys (15.1±0.4 y) completed three 3-day experimental trials in a randomised order: 1) 8×1 min cycling at 90% peak power with 75 s recovery (HIIE); 2) cycling at 90% of gas exchange threshold for a duration to match work during HIIE (MIE); and 3) rest (CON). Plasma [glucose] and [insulin] were measured before (PRE-Ex), 24 and 48 h post (24 h-POST, 48 h-POST) in a fasted state, and 40 min (POST-Ex) and 24 h (24 h-POST) post in response to an oral glucose tolerance test (OGTT). IS was estimated using the Cederholm (OGTT) and HOMA (fasted) indices. There was no change to HOMA at 24 h or 48 h-POST (all Pandgt;0.05). IS from the OGTT was higher POST-EX for HIIE compared to CON (17.4%, P0.010, ES1.06), and a non-significant increase in IS after MIE compared to CON (9.0%, P0.14, ES0.59). At 24 h-POST, IS was higher following both HIIE and MIE compared to CON (HIIE: P0.019, 13.2%, ES0.88; MIE: 9.7%, P0.024, ES0.65). In conclusion, improvements to IS after a single bout of HIIE and MIE persist up to 24 h after exercise when assessed by OGTT.
 Abstract.  Author URL Full text
Cockcroft EJ, Moudiotis C, Kitchen J, Bond B, Williams CA, Barker AR (2017). High-intensity interval exercise and glycemic control in adolescents with type one diabetes mellitus: a case study. Physiol Rep, 5(13).

Abstract:
High-intensity interval exercise and glycemic control in adolescents with type one diabetes mellitus: a case study.

Current physical activity guidelines for youth with type 1 diabetes (T1D) are poorly supported by empirical evidence and the optimal dose of physical activity to improve glycemic control is unknown. This case report documents the effect of acute high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE) on 24-h glycemic control in three adolescents with T1D using continuous glucose monitoring. Results highlight varied individual response to exercise across the participants. In two participants both MIE and HIIE resulted in a drop in blood glucose during exercise (-38 to -42% for MIE and -21-46% in HIIE) and in one participant both MIE and HIIE resulted in increased blood glucose (+19% and + 36%, respectively). Over the 24-h period average blood glucose was lower for all participants in the HIIE condition, and for two for the MIE condition, compared to no exercise. All three participants reported HIIE to be more enjoyable than MIE These data show both HIIE and MIE have the potential to improve short-term glycemic control in youth with T1D but HIIE was more enjoyable. Future work with a larger sample size is required to explore the potential for HIIE to improve health markers in youth with T1D.
 Abstract.  Author URL Full text

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