Medicine & Science in Sports & Exercise, 2022
Purpose Exercise training is recommended to improve cardiometabolic health and fertility in women... more Purpose Exercise training is recommended to improve cardiometabolic health and fertility in women with polycystic ovary syndrome (PCOS), yet there are few randomized controlled trials on the effects of different exercise protocols on clinical reproductive outcomes. Our aim was to determine the effect of high-intensity interval training (HIT) on menstrual frequency, as a proxy of reproductive function, in women with PCOS. Methods The IMPROV-IT study was a two-center randomized controlled trial undertaken in Norway and Australia. Women with PCOS were eligible for inclusion. After stratification for body mass index <27 or ≥27 kg·m−2 and study center, participants were randomly allocated (1:1:1) to high-volume HIT (HV-HIT), low-volume HIT (LV-HIT), or a control group. Measurements were assessed at baseline, after the 16-wk exercise intervention, and at 12-month follow-up. The primary outcome was menstrual frequency after 12 months. Secondary outcomes included markers of cardiometabol...
Individuals with type 2 diabetes (T2D) require a long-term dietary strategy for blood glucose man... more Individuals with type 2 diabetes (T2D) require a long-term dietary strategy for blood glucose management and may benefit from time-restricted eating (TRE, where the duration between the first and last energy intake is restricted to 8–10 h/day). We aimed to determine the feasibility of TRE for individuals with T2D. Participants with T2D (HbA1c >6.5 to <9%, eating window >12 h/day) were recruited to a pre-post, non-randomised intervention consisting of a 2-week Habitual period to establish baseline dietary intake, followed by a 4-weeks TRE intervention during which they were instructed to limit all eating occasions to between 10:00 and 19:00 h on as many days of each week as possible. Recruitment, retention, acceptability, and safety were recorded throughout the study as indicators of feasibility. Dietary intake, glycaemic control, psychological well-being, acceptability, cognitive outcomes, and physiological measures were explored as secondary outcomes. From 594 interested p...
Time-restricted feeding (TRF) improves metabolism independent of dietary macronutrient compositio... more Time-restricted feeding (TRF) improves metabolism independent of dietary macronutrient composition or energy restriction. To elucidate mechanisms underpinning the effects of short-term TRF, we investigated skeletal muscle and serum metabolic and transcriptomic profiles from 11 men with overweight/obesity after TRF (8 h day−1) and extended feeding (EXF, 15 h day−1) in a randomised cross-over design (trial registration: ACTRN12617000165381). Here we show that muscle core clock gene expression was similar after both interventions. TRF increases the amplitude of oscillating muscle transcripts, but not muscle or serum metabolites. In muscle, TRF induces rhythmicity of several amino acid transporter genes and metabolites. In serum, lipids are the largest class of periodic metabolites, while the majority of phase-shifted metabolites are amino acid related. In conclusion, short-term TRF in overweight men affects the rhythmicity of serum and muscle metabolites and regulates the rhythmicity o...
We determined the effects of time-restricted feeding (TRF; 8 h/d) versus extended feeding (EXF; 1... more We determined the effects of time-restricted feeding (TRF; 8 h/d) versus extended feeding (EXF; 15 h/d) on 24-h and postprandial metabolism and subjective opinions of TRF in men with overweight/obesity. In a randomized crossover design, 11 sedentary males (age 38 ± 5 y; BMI: 32.2 ± 2.0 kg/m2) completed two isoenergetic diet protocols for 5 days, consuming meals at 1000, 1300 and 1700 h (TRF) or 0700, 1400 and 2100 h (EXF). On Day 5, participants remained in the laboratory for 24 h, and blood samples were collected at hourly (0700–2300 h) then 2-hourly (2300–0700 h) intervals for concentrations of glucose, insulin and appetite/incretin hormones. Structured qualitative interviews were conducted following completion of both dietary conditions and investigated thematically. Total 24-h area under the curve (AUCtotal) [glucose] tended to be lower for TRF versus EXF (−5.5 ± 9.0 mmol/L/h, p = 0.09). Nocturnal glucose AUC was lower in TRF (−4.2 ± 5.8 mmol/L/h, p = 0.04), with no difference i...
IntroductionPolycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproduct... more IntroductionPolycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age and the leading cause of anovulatory infertility. Women with PCOS have a 15-fold higher prevalence of infertility, compared with women without PCOS, independent of body mass index (BMI). A healthy lifestyle is recommended to improve overall health and fertility in PCOS but there is limited evidence on the isolated effects of exercise, especially for reproductive outcomes. Previous findings indicate superior metabolic health benefits after vigorous compared with moderate-intensity exercise. Our primary aim is to determine the effect of high-intensity interval training (HIT) on menstrual frequency, as a proxy of reproductive function, in women with PCOS.Methods and analysisThe study is a two-centre, randomised, controlled trial with three parallel groups. Women (n=64) from Trondheim (Norway) and Melbourne (Australia) with PCOS according to the Rotterdam criteria will be randomly al...
Estrogen (E2) and polyunsaturated fatty acids (n-3PUFA) supplements independently support general... more Estrogen (E2) and polyunsaturated fatty acids (n-3PUFA) supplements independently support general wellbeing and enhance muscle regeneration in-vivo and myotube formation in-vitro. However, the combined effect of E2 and n-3PUFA on myoblast differentiation is not known. The purpose of the study was to identify whether E2 and n-3PUFA possess a synergistic effect on in-vitro myogenesis. Mouse C2C12 myoblasts, a reliable model to reiterate myogenic events in-vitro, were treated with 10nM E2 and 50μM eicosapentaenoic acid (EPA) independently or combined, for 0–24 h or 0–120 h during differentiation. Immunofluorescence, targeted qPCR and next generation sequencing (NGS) were used to characterize morphological changes and differential expression of key genes involved in the regulation of myogenesis and muscle function pathways. E2 increased estrogen receptor α (Erα) and the expression of the mitogen-activated protein kinase 11 (Mapk11) within 1 h of treatment and improved myoblast different...
Climate change is a major contributor to annual winter peaks in cardiovascular events across the ... more Climate change is a major contributor to annual winter peaks in cardiovascular events across the globe. However, given the paradoxical observation that cardiovascular seasonality is observed in relatively mild as well as cold climates, global warming may not be as positive for the syndrome of heart failure (HF) as some predict. In this article, we present our Model of Seasonal Flexibility to explain the spectrum of individual responses to climatic conditions. We have identified distinctive phenotypes of resilience and vulnerability to explain why winter peaks in HF occur. Moreover, we identify how better identification of climatic vulnerability and the use of multifaceted interventions focusing on modifiable bio-behavioural factors may improve HF outcomes.
Chronic overconsumption of sugar-sweetened beverages (SSBs) is associated with unfavourable healt... more Chronic overconsumption of sugar-sweetened beverages (SSBs) is associated with unfavourable health effects, including promotion of obesity. However, the acute effects of consuming SSBs on glucose and lipid metabolism remain to be characterized in a real-world, post-prandial context of prolonged sitting. We quantified the acute effects of between-meal SSB consumption compared with water, on glucose and lipid metabolism in habitual soft drink consumers during prolonged sitting. Twenty-eight overweight or obese young adults [15 males; 23 ± 3 (mean ± SD) years, body mass index (BMI) 31.0 ± 3.6 kg/m) participated. During uninterrupted sitting and following standardized breakfast and lunch meals, each participant completed two 7-h conditions on separate days in a randomized, crossover design study. For each condition, participants consumed either a sucrose SSB or water mid-morning and mid-afternoon. Peak responses and total area under the curve (tAUC) over 7 h for blood glucose, insulin, ...
We compared the impact of a high versus low energy intake first meal on glucose and insulin respo... more We compared the impact of a high versus low energy intake first meal on glucose and insulin responses during prolonged sitting in individuals with prediabetes. Thirteen adults with overweight/obesity and prediabetes (mean ± SD age: 60 ± 6 years, BMI: 33 ± 4 kg/m²; 2 h OGTT: 8.9 ± 1.1 mmol/L) completed two randomised trials: 10 h uninterrupted sitting, incorporating three meals with matching macronutrient compositions but different energy distributions: High-Energy Breakfast (HE-BF; breakfast: 50%, lunch: 30%, dinner: 20% energy intake), Low-Energy Breakfast (LE-BF: 20%/30%/50% energy intake). Venous blood was sampled from 08:00⁻18:00 h for determination of plasma glucose and insulin concentrations, with 24 h continuous glucose monitoring (CGM). Total glucose area under the curve (AUC; +5.7 mmol/L/h, = 0.019) and mean plasma glucose concentrations (+0.5 mmol/L, = 0.014) were greater after HE-BF compared to LE-BF. In the HE-BF condition, compared to LE-BF, there was a greater incremen...
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, 2000
The stress electrocardiogram (sECG) is routinely used to screen individuals for underlying cardia... more The stress electrocardiogram (sECG) is routinely used to screen individuals for underlying cardiac pathology before an exercise programme is prescribed. The underlying assumption is that the cardiac responses elicited during the sECG test are similar to those achieved during participation in sporting activities. However, this premise may be incorrect since the physical demands of different modes of exercise vary substantially. Ten veteran league squash players (LSP), 10 social squash players (SSP), 10 league runners (LR), 10 social runners (SR) and 10 sedentary individuals (SED) were recruited for the study. All subjects completed a lifestyle questionnaire, a full medical examination and a routine sECG. Thereafter each subject's heart rate (HR) was monitored on two separate occasions while participating in sporting activity. No sECG exercise-induced abnormalities were observed, although five subjects showed resting abnormalities. Maximal HR during the sECG, and maximal and mean ...
Medicine & Science in Sports & Exercise, 2022
Purpose Exercise training is recommended to improve cardiometabolic health and fertility in women... more Purpose Exercise training is recommended to improve cardiometabolic health and fertility in women with polycystic ovary syndrome (PCOS), yet there are few randomized controlled trials on the effects of different exercise protocols on clinical reproductive outcomes. Our aim was to determine the effect of high-intensity interval training (HIT) on menstrual frequency, as a proxy of reproductive function, in women with PCOS. Methods The IMPROV-IT study was a two-center randomized controlled trial undertaken in Norway and Australia. Women with PCOS were eligible for inclusion. After stratification for body mass index <27 or ≥27 kg·m−2 and study center, participants were randomly allocated (1:1:1) to high-volume HIT (HV-HIT), low-volume HIT (LV-HIT), or a control group. Measurements were assessed at baseline, after the 16-wk exercise intervention, and at 12-month follow-up. The primary outcome was menstrual frequency after 12 months. Secondary outcomes included markers of cardiometabol...
Individuals with type 2 diabetes (T2D) require a long-term dietary strategy for blood glucose man... more Individuals with type 2 diabetes (T2D) require a long-term dietary strategy for blood glucose management and may benefit from time-restricted eating (TRE, where the duration between the first and last energy intake is restricted to 8–10 h/day). We aimed to determine the feasibility of TRE for individuals with T2D. Participants with T2D (HbA1c >6.5 to <9%, eating window >12 h/day) were recruited to a pre-post, non-randomised intervention consisting of a 2-week Habitual period to establish baseline dietary intake, followed by a 4-weeks TRE intervention during which they were instructed to limit all eating occasions to between 10:00 and 19:00 h on as many days of each week as possible. Recruitment, retention, acceptability, and safety were recorded throughout the study as indicators of feasibility. Dietary intake, glycaemic control, psychological well-being, acceptability, cognitive outcomes, and physiological measures were explored as secondary outcomes. From 594 interested p...
Time-restricted feeding (TRF) improves metabolism independent of dietary macronutrient compositio... more Time-restricted feeding (TRF) improves metabolism independent of dietary macronutrient composition or energy restriction. To elucidate mechanisms underpinning the effects of short-term TRF, we investigated skeletal muscle and serum metabolic and transcriptomic profiles from 11 men with overweight/obesity after TRF (8 h day−1) and extended feeding (EXF, 15 h day−1) in a randomised cross-over design (trial registration: ACTRN12617000165381). Here we show that muscle core clock gene expression was similar after both interventions. TRF increases the amplitude of oscillating muscle transcripts, but not muscle or serum metabolites. In muscle, TRF induces rhythmicity of several amino acid transporter genes and metabolites. In serum, lipids are the largest class of periodic metabolites, while the majority of phase-shifted metabolites are amino acid related. In conclusion, short-term TRF in overweight men affects the rhythmicity of serum and muscle metabolites and regulates the rhythmicity o...
We determined the effects of time-restricted feeding (TRF; 8 h/d) versus extended feeding (EXF; 1... more We determined the effects of time-restricted feeding (TRF; 8 h/d) versus extended feeding (EXF; 15 h/d) on 24-h and postprandial metabolism and subjective opinions of TRF in men with overweight/obesity. In a randomized crossover design, 11 sedentary males (age 38 ± 5 y; BMI: 32.2 ± 2.0 kg/m2) completed two isoenergetic diet protocols for 5 days, consuming meals at 1000, 1300 and 1700 h (TRF) or 0700, 1400 and 2100 h (EXF). On Day 5, participants remained in the laboratory for 24 h, and blood samples were collected at hourly (0700–2300 h) then 2-hourly (2300–0700 h) intervals for concentrations of glucose, insulin and appetite/incretin hormones. Structured qualitative interviews were conducted following completion of both dietary conditions and investigated thematically. Total 24-h area under the curve (AUCtotal) [glucose] tended to be lower for TRF versus EXF (−5.5 ± 9.0 mmol/L/h, p = 0.09). Nocturnal glucose AUC was lower in TRF (−4.2 ± 5.8 mmol/L/h, p = 0.04), with no difference i...
IntroductionPolycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproduct... more IntroductionPolycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age and the leading cause of anovulatory infertility. Women with PCOS have a 15-fold higher prevalence of infertility, compared with women without PCOS, independent of body mass index (BMI). A healthy lifestyle is recommended to improve overall health and fertility in PCOS but there is limited evidence on the isolated effects of exercise, especially for reproductive outcomes. Previous findings indicate superior metabolic health benefits after vigorous compared with moderate-intensity exercise. Our primary aim is to determine the effect of high-intensity interval training (HIT) on menstrual frequency, as a proxy of reproductive function, in women with PCOS.Methods and analysisThe study is a two-centre, randomised, controlled trial with three parallel groups. Women (n=64) from Trondheim (Norway) and Melbourne (Australia) with PCOS according to the Rotterdam criteria will be randomly al...
Estrogen (E2) and polyunsaturated fatty acids (n-3PUFA) supplements independently support general... more Estrogen (E2) and polyunsaturated fatty acids (n-3PUFA) supplements independently support general wellbeing and enhance muscle regeneration in-vivo and myotube formation in-vitro. However, the combined effect of E2 and n-3PUFA on myoblast differentiation is not known. The purpose of the study was to identify whether E2 and n-3PUFA possess a synergistic effect on in-vitro myogenesis. Mouse C2C12 myoblasts, a reliable model to reiterate myogenic events in-vitro, were treated with 10nM E2 and 50μM eicosapentaenoic acid (EPA) independently or combined, for 0–24 h or 0–120 h during differentiation. Immunofluorescence, targeted qPCR and next generation sequencing (NGS) were used to characterize morphological changes and differential expression of key genes involved in the regulation of myogenesis and muscle function pathways. E2 increased estrogen receptor α (Erα) and the expression of the mitogen-activated protein kinase 11 (Mapk11) within 1 h of treatment and improved myoblast different...
Climate change is a major contributor to annual winter peaks in cardiovascular events across the ... more Climate change is a major contributor to annual winter peaks in cardiovascular events across the globe. However, given the paradoxical observation that cardiovascular seasonality is observed in relatively mild as well as cold climates, global warming may not be as positive for the syndrome of heart failure (HF) as some predict. In this article, we present our Model of Seasonal Flexibility to explain the spectrum of individual responses to climatic conditions. We have identified distinctive phenotypes of resilience and vulnerability to explain why winter peaks in HF occur. Moreover, we identify how better identification of climatic vulnerability and the use of multifaceted interventions focusing on modifiable bio-behavioural factors may improve HF outcomes.
Chronic overconsumption of sugar-sweetened beverages (SSBs) is associated with unfavourable healt... more Chronic overconsumption of sugar-sweetened beverages (SSBs) is associated with unfavourable health effects, including promotion of obesity. However, the acute effects of consuming SSBs on glucose and lipid metabolism remain to be characterized in a real-world, post-prandial context of prolonged sitting. We quantified the acute effects of between-meal SSB consumption compared with water, on glucose and lipid metabolism in habitual soft drink consumers during prolonged sitting. Twenty-eight overweight or obese young adults [15 males; 23 ± 3 (mean ± SD) years, body mass index (BMI) 31.0 ± 3.6 kg/m) participated. During uninterrupted sitting and following standardized breakfast and lunch meals, each participant completed two 7-h conditions on separate days in a randomized, crossover design study. For each condition, participants consumed either a sucrose SSB or water mid-morning and mid-afternoon. Peak responses and total area under the curve (tAUC) over 7 h for blood glucose, insulin, ...
We compared the impact of a high versus low energy intake first meal on glucose and insulin respo... more We compared the impact of a high versus low energy intake first meal on glucose and insulin responses during prolonged sitting in individuals with prediabetes. Thirteen adults with overweight/obesity and prediabetes (mean ± SD age: 60 ± 6 years, BMI: 33 ± 4 kg/m²; 2 h OGTT: 8.9 ± 1.1 mmol/L) completed two randomised trials: 10 h uninterrupted sitting, incorporating three meals with matching macronutrient compositions but different energy distributions: High-Energy Breakfast (HE-BF; breakfast: 50%, lunch: 30%, dinner: 20% energy intake), Low-Energy Breakfast (LE-BF: 20%/30%/50% energy intake). Venous blood was sampled from 08:00⁻18:00 h for determination of plasma glucose and insulin concentrations, with 24 h continuous glucose monitoring (CGM). Total glucose area under the curve (AUC; +5.7 mmol/L/h, = 0.019) and mean plasma glucose concentrations (+0.5 mmol/L, = 0.014) were greater after HE-BF compared to LE-BF. In the HE-BF condition, compared to LE-BF, there was a greater incremen...
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, 2000
The stress electrocardiogram (sECG) is routinely used to screen individuals for underlying cardia... more The stress electrocardiogram (sECG) is routinely used to screen individuals for underlying cardiac pathology before an exercise programme is prescribed. The underlying assumption is that the cardiac responses elicited during the sECG test are similar to those achieved during participation in sporting activities. However, this premise may be incorrect since the physical demands of different modes of exercise vary substantially. Ten veteran league squash players (LSP), 10 social squash players (SSP), 10 league runners (LR), 10 social runners (SR) and 10 sedentary individuals (SED) were recruited for the study. All subjects completed a lifestyle questionnaire, a full medical examination and a routine sECG. Thereafter each subject's heart rate (HR) was monitored on two separate occasions while participating in sporting activity. No sECG exercise-induced abnormalities were observed, although five subjects showed resting abnormalities. Maximal HR during the sECG, and maximal and mean ...
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Papers by John Hawley