Background
Methods
Study design
Participants
Inclusion Criteria | Exclusion Criteria |
---|---|
• Aged 9–15 years. • Inactive (self-reported as inactive; no specific criteria applied). • Participant and parent or guardian able to support lifestyle changes and commit to a 12-week program between July – October 2018 with an intention of ≥80% attendance of all Project GRIT sessions. | • Known diagnosis of learning disorder and/or medical condition with which the multidisciplinary Project GRIT staff cannot provide sufficient support for, including: Attention Deficit Hyperactivity Disorder, Autism, Asperger Syndrome, Tourette Syndrome, or Bipolar Disorder. • Known diagnosis of a medical condition which contraindicates high-intensity exercise, including: o Hypertension as defined by systolic and/or diastolic blood pressure ≥ 95th percentile measured upon three or more occasions o History or evidence of cardiac abnormalities or family history of hypertrophic obstructive cardiomyopathy o Hypercholesterolaemia o Chronic disease including but not limited to kidney disease, chronic asthma, diabetes (type I or II) o Orthopaedic or neurological disorder which limits physical activity o Pulmonary disease • Current smoker • Use of steroid medications • Food allergy which would prevent the child from involvement in healthy eating or cooking demonstration sessions |
GRIT intervention
Week of program | HIIT Exercise | Diet | Psychology |
---|---|---|---|
Number of sessions offered | |||
1 | 3 | 1 | |
2 | 3 | ||
3 | 3 | 1 | |
4 | 3 | ||
5 | 3 | 1 | |
6 | 3 | 1 | |
7 | 2 | ||
8 | 3 | 1 | |
9 | 2 | ||
10 | 2 | 1 | |
11 | 3 | ||
12 | 3 |
Exercise sessions
-
15-s high intensity activity at ≥85% HRmax with 2.45-min recovery at 50–70% HRmax.
-
30-s high intensity activity at ≥85% HRmax with 4.30-min recovery at 50–70% HRmax.
-
1-min high intensity activity at ≥85% HRmax with 5-min recovery at 50–70% HRmax.
Heart rate monitoring
Healthy eating and cooking demonstration workshops
Emotional freedom technique and mindfulness workshop
Study measures
Study Measure | Timepoints | Explanation | Related intervention component/s |
---|---|---|---|
Attendance | All sessions from baseline to 12 weeks | Measure of feasibility | All |
Retention | 1st exercise session to last attended study session | Measure of feasibility Total days involved and number of participants completing the study versus withdrawal | Program involvement |
Adverse events | Reported at any exercise, dietary or psychology session | Measure of feasibility Minor or major Assessed whether unrelated, potentially related or related to the study | All |
Satisfaction | 12 weeks or at withdrawal | Measure of feasibility Collected via written surveys with Likert scaled questions | All |
Heart rate during exercise sessions | Continuously during HIIT group exercise sessions and individual make-up sessions | Guide for participants during exercise sessions to achieve high intensity and recovery heart rate targets Changes in HR across the intervention are a fitness indicator | Exercise sessions |
Anthropometry | Baseline | Participant characteristics for weight, height and waist circumference, with calculation of BMI, BMI-for-age percentiles and Z-score | Not a target of any interventions |
Maximal graded cardiorespiratory testing | Baseline and 12 weeks | VO2peak: Peak oxygen consumption during testing as a measure of maximal exercise capacity. Testing time to reach VO2peak measures time to exertion. HRmax: Maximum heart rate measured during exercise testing. A reduction in HRmax over time can indicate improvements in cardiac output. MFO: maximum fat oxidation measure during testing, positively associated with respiratory capacity and training status [36]. | Exercise sessions |
Australian Child and Adolescent Eating Survey FFQ (Nutrient intake and diet quality) | Baseline and 12 weeks | Total and food-group based Australian Child and Adolescent Recommended Food Scores, measures of diet quality reflecting adherence to the Australian Dietary Guidelines. Estimated daily intake of food groups as a percentage contribution to total energy intake. Estimated macro- and micronutrient intake | Dietary education sessions and cooking demonstrations |
Piers Harris-2 Self-concept scale | Baseline and 12 weeks | Global measure of self-esteem. Measures total and domains of behavioural adjustment, intellectual and school status, physical appearance and attributes, popularity, happiness and satisfaction, and freedom from anxiety | All |
Process evaluation
Heart rate during exercise sessions
Anthropometry
Maximal graded cardiorespiratory testing
Nutrient intake and diet quality
Psychological assessment: self-concept
Statistical analyses
Results
Participants
Measure | Total cohort |
---|---|
Median (IQR)a, n (%), or mean ± SD | |
Age (years) | 11.4 (9.7–12.9) |
Male sex | 20 (53) |
Sibling involved | 16 (42) |
Weight (kg) | 56.7 ± 18.7 |
Waist circumference (cm) | 76.7 ± 13.7 |
BMI (kg/m2) | 23.5 ± 5.5 |
BMI for age (%le) | 95 (47–98) |
BMI Z-score | 1.6 (−0.10–1.99) |
< −1 | 1 (42) |
−1 to 1 | 12 (32) |
> 1 to 2 | 16 (42) |
> 2 | 9 (24) |
Exercise sessions/week | 2.0 (1.0–3.0) |
Process evaluation
Program attendance
Measure | Total cohort (n = 38) | Completers (n = 24) | ||
---|---|---|---|---|
No. sessions | % of offered | No. sessions | % of offered | |
Exercise sessions (out of 33)a | 17.5 (5.0–20.5) | 53 (15–62) | 19.0 (18.0–25.0) | 58 (55–75) |
Weeks 1–4 (out of 12) | 8.5 (5.0–10.3) | 71 (42–85) | 9.0 (8.3–11.0) | 75 (69–92) |
Weeks 5–8 (out of 11) | 6.0 (0–7.3) | 55 (0–66) | 7.0 (6.0–8.0) | 64 (55–73) |
Weeks 9–12 (out of 10) | 2.0 (0–5.0) | 20 (0–50) | 4.5 (2.3–6.0) | 45 (23–60) |
Dietary sessions (out of 5) | 2.0 (1.0–4.0) | 40 (20–80) | 3.1 (2.0–4.8) | 60 (40–95) |
EFT/Mindfulness session (out of 1) | n = 10 | 26% | n = 10 | 42% |
Adverse events
Satisfaction surveys
Heat rate during exercise sessions
HR Measure | Weeks 2-4a | Weeks 5–8 | Weeks 9–12 | |
---|---|---|---|---|
Mean ± SD | p-value | |||
Minimum | 111 ± 11 | 110 ± 7 | 109 ± 9 | 0.23 |
Maximum | 191 ± 8 | 193 ± 8 | 196 ± 9 | 0.001* |
Mean | 147 ± 9 | 144 ± 7 | 146 ± 8 | 0.06 |
Mean % HRmax | 75 ± 5 | 73 ± 4 | 74 ± 5 | 0.046** |
Study outcome measures
Maximal graded cardiorespiratory testing
Measure | Baseline | 12-weeks | |
---|---|---|---|
Mean ± SD or Median (IQR)c | p-value | ||
Test duration (min:sec) | 19:41 ± 2:00 | 19:52 ± 01:09 | 0.63 |
VO2peak (absolute, ml/min) | 1922 ± 469 | 2018 ± 468 | 0.06 |
VO2peak time (min:sec) | 19:13 ± 02:06 | 19:32 ± 01:12 | 0.38 |
HR exercise start (bpm) | 110 ± 14 | 111 ± 11 | 0.93 |
HRmax (bpm) | 201 (192–205) | 198 (192–203) | 0.58 |
HRmax test time (min:sec) | 19:19 ± 02:05 | 19:28 ± 01:05 | 0.67 |
aMFO (kcal/min) | 2.7 ± 1.0 | 2.4 ± 0.9 | 0.12 |
bMFO time (1 min interval) | 13 (11–15) | 12 (10–17) | 0.76 |
Nutrient intake and diet quality
Measure | Baseline | 12-weeks | |
---|---|---|---|
Mean ± SD or Median (IQR)a | p-value | ||
Food Percentage Contribution to Daily Energy Intake | |||
Core | 55.7 ± 17.0 | 61.7 ± 12.4 | 0.02* |
Non-core | 44.3 ± 17.0 | 38.4 ± 12.4 | 0.02* |
Vegetables | 4.0 (2.0–5.0) | 4.5 (2.0–7.0) | 0.38 |
Fruit | 7.8 ± 4.3 | 10.1 ± 7.4 | 0.12 |
Grains | 15.0 (8.0–19.0) | 15.5 (10.3–18.8) | 0.86 |
Meat | 12.6 ± 6.0 | 14.7 ± 7.8 | 0.21 |
Meat alternatives | 2.0 (1.0–5.0) | 2.0 (1.0–4.8) | 0.64 |
Dairy | 9.0 (8.0–17.0) | 11.5 (7.0–22.0) | 0.41 |
Sweet drinks | 3.0 (1.0–5.0) | 2.0 (1.0–4.8) | 0.89 |
Packaged snacks | 6.0 (3.0–10.0) | 4.5 (3.0–9.8) | 0.73 |
Confectionary | 6.0 (4.0–12.0) | 5.0 (4.0–8.8) | 0.003* |
Baked products | 6.0 (4.0–9.0) | 5.0 (3.0–7.0) | 0.02* |
Takeaway | 9.0 (8.0–16.0) | 10.0 (9.0–16.8) | 0.78 |
Condiments | 2.0 (1.0–3.0) | 2.0 (1.0–3.0) | 0.12 |
Fatty meats | 2.0 (1.0–3.0) | 2.0 (1.0–3.0) | 0.23 |
Australian Recommended Food Scores | |||
Total (/73) | 23.0 (18.0–35.0) | 26.0 (19.3–39.5) | 0.28 |
Vegetables (/21) | 7.3 ± 5.0 | 6.8 ± 4.9 | 1.00 |
Fruit (/12) | 4.0 (3.0–7.0) | 5.0 (2.3–7.8) | 0.25 |
Grains (/13) | 4.6 ± 2.1 | 4.8 ± 2.5 | 0.13 |
Meat (/7) | 2.3 ± 1.1 | 2.4 ± 1.6 | 0.73 |
Meat alternatives (/6) | 1.0 (1.0–2.0) | 2.0 (1.0–2.0) | 0.79 |
Dairy (/11) | 3.7 ± 2.2 | 4.0 ± 2.4 | 0.12 |
Extras (/1) | 1.0 (1.0–2.0) | 1.0 (1.0–2.0) | 1.00 |
Water (/2) | 1.0 (0.0–1.0) | 1.0 (1.0–1.0) | 0.66 |
Daily Nutrient Intake | |||
Energy (kJ) | 9078 ± 2689 | 8663 ± 3507 | 0.52 |
Protein (g) | 94.4 ± 28.8 | 96.7 ± 42.9 | 0.75 |
Protein (%E) | 17.0 (16.0–19.0) | 18.0 (17.0–21.8) | 0.39 |
CHO (g) | 252.3 ± 79.9 | 230.1 ± 93.4 | 0.23 |
CHO (%E) | 47.7 ± 5.7 | 45.9 ± 8.6 | 0.31 |
Fat (g) | 83.5 ± 28.5 | 80.9 ± 36.5 | 0.71 |
Fat (%E) | 35.4 ± 4.8 | 35.3 ± 6.1 | 0.86 |
Saturated fat (g) | 38.1 ± 14.7 | 35.9 ± 17.7 | 0.53 |
Saturated fat (%E) | 15.9 ± 3.0 | 15.3 ± 3.4 | 0.52 |
PUFA (g) | 8.9 ± 2.9 | 8.6 ± 4.1 | 0.93 |
PUFA (%E) | 4.0 (3.0–4.0) | 4.0 (3.3–4.0) | 0.59 |
MUFA (g) | 29.4 ± 9.9 | 27.4 ± 13.8 | 0.89 |
MUFA (%E) | 12.4 ± 2.0 | 12.8 ± 2.5 | 0.52 |
Cholesterol (mg) | 326.4 ± 114.4 | 303.0 ± 172.9 | 0.81 |
Sugars (g) | 131.1 ± 55.8 | 105.4 ± 48.1 | 0.18 |
Water (L) | 2.2 ± 0.7 | 2.1 ± 1.0 | 0.63 |
Fibre (g) | 22.1 (22.2–29.9) | 23.7 (15.3–30.6) | 0.99 |
Vitamin C (mg) | 86.2 (53.0–264.8) | 110.2 (57.1–150.5) | 0.40 |
Folate (μg) | 235.0 (235.0–359.7) | 256.9 (173.7–353.3) | 0.86 |
Niacin (mg) | 21.2 ± 6.7 | 21.2 ± 9.2 | 0.99 |
Niacin equivalents (mg) | 40.1 ± 11.8 | 40.6 ± 17.5 | 0.86 |
Riboflavin (mg) | 2.2 ± 0.9 | 2.2 ± 1.1 | 0.87 |
Thiamin (mg) | 1.6 (0.8–1.8) | 1.5 (0.9–2.1) | 0.52 |
Vitamin A (μg) | 1145.7 (802.5–1614.7) | 1261.9 (771.1–1753.0) | 0.71 |
Retinol (μg) | 497.3 (306.5–632.8) | 429.3 (429.3–700.0) | 0.58 |
Beta-carotene (μg) | 3694.0 (1974.7–5720.7) | 4092.9 (1487.9–6383.2) | 1.00 |
Sodium (mg) | 2197.8 ± 702.1 | 2141.3 ± 999.0 | 0.76 |
Potassium (mg) | 3093.0 ± 997.4 | 3104.2 ± 1306.4 | 0.96 |
Magnesium (mg) | 332.4 ± 88.1 | 339.2 ± 130.4 | 0.75 |
Phosphorus (mg) | 1578.1 ± 513.3 | 1589.6 ± 723.5 | 0.93 |
Iron (mg) | 12.1 ± 3.7 | 12.1 ± 4.7 | 0.97 |
Zinc (mg) | 12.3 ± 3.6 | 12.7 ± 5.5 | 0.62 |
Calcium (mg) | 987.6 (713.7–1318.6) | 906.5 (601.1–1695.9) | 0.61 |
Self-concept
Scale | Baseline | 12-weeksb | |
---|---|---|---|
Mean ± SD or Median (IQR)c | p-value | ||
Total score | 48.2 ± 9.4 | 51.0 ± 10.8 | 0.02* |
Behavioural adjustment | 54.0 (46.8–62.0) | 54.0 (49.0–62.0) | 0.30 |
Intellectual and school status | 51.0 (48.0–54.0) | 51.0 (46.0–54.0) | 0.39 |
Physical appearance and attributes | 42.0 (40.0–50.3) | 48.0 (40.5–54.3) | 0.02* |
Freedom from anxiety | 47.0 (37.0–54.0) | 52.5 (37.0–58.0) | 0.08 |
Popularity | 47.0 ± 10.4 | 47.3 ± 9.8 | 0.62 |
Happiness and satisfaction | 45.0 (40.0–51.0) | 49.0 (40.0–59.0) | 0.10 |
Response bias | 49.2 ± 10.5 | 49.8 ± 9.6 | 0.85 |
Inconsistent responding | 53.0 (43.0–53.0) | 43.0 (43.0–53.0) | 0.29 |