Reducing fatigue following acquired brain injury: A feasibility study of high intensity interval training for young adults

Figures & data

Table 1. Procedures of the high intensity interval training program

Contents of sessions		Week 1–2		Week 3–4		Week 5–6
Set	Intensity ^a	No.	Min.	No.	Min.	No.	Min.
Warm-up	Low	1	5	1	5	1	5
Warm-up	Medium	1	5	1	5	1	5
“All-out” intervals	High	4	0.5	5	0.5	6	0.5
Breaks in-between intervals	Low	3	4	4	3.5	5	3.5
Cool-down, optional	Low	0–1	2	0–1	2	0–1	2

Note. Sessions were repeated three times a week for six weeks. Each session was introduced by a 10 min. warm-up followed by an increasing number of intermittent high intensity intervals. Watt, pulse, and Borg measures were recorded at each set to guide load adjustments. No. = number of sets per session; min. = minutes (per each number of set).

^aLow = 45–55% of watt max; Medium = 55–60% of watt max; High = ≥ 90% of watt max.

Figure 1. Flowchart of participants.

Table 2. Baseline characteristics

Variable	Completed intervention (n = 6)	Discontinuedintervention (n = 4)
Age, mean (SD)	30 (7.0)	23 (2.7)
Sex, n
Male	0	3
Female	6	1
Occupation, n
Work/study (normal conditions)	1	2
Work/study (special conditions)	3	0
Sick leave	2	1
Unemployed	0	1
Living arrangement, n (%)
Cohabitation	1	1
Married	1	0
Living with parents	0	2
Living alone	4	1
Highest educational level
Elementary	1	3
9–12 years	3	1
> 12 years	2	0
Type of injury
Traumatic brain injury	3	1
Stroke	1	2
Tumor	1	1
Meningitis	1	0
Months since injury, mean (SD) ^a	22.0 (18.9)	33.3 (39.8)
Body mass (kg), mean (SD)	66.4 (1.6)	86.3 (13.5)
Smoker, n (%)	2 (33)	2 (50)

Note.

^aIf tumor, the date of injury was defined as the day of neurosurgery.

Table 3. Minutes of weekly physical activity and exercise in the study period

	Baseline			Post-intervention			Follow-up
ID	Easy	Moderate	Hard	Easy	Moderate	Hard	Easy	Moderate	Hard	Type of exercise ^a
2	630	60	60	480	390	90	300	90	120	Running
5	720	300	0	570	360	90	-	-	-	-
6	240	0	60	420	0	240	150	90	210	Running & cycling
7	1260	840	0	1260	0	90	900	0	0	None
9	1680	420	0	600	120	90	600	120	60	Running
10	300	180	0	360	0	90	360	180	0	Fitness training
Total	4830	1800	120	3690	870	690	-	-	-	-

Note. Examples of easy physical activity included walks, easy cleaning, sweeping and raking in the garden, and easy exercise such as yoga, bowling, etc.; Moderate physical activity included gardening, carrying something up the stairs, and moderate exercise such as gymnastics, swimming, cycling, weightlifting, etc.; Hard physical activity included tiring sports and exercise such as running, jogging, football, tennis, aerobic, etc.

^aInformation on current exercise behavior was collected during follow-up interviews.

Figure 2. Indicators of feasibility and adherence during high intensity interval training.

Note. Part B, C, and D shows data recorded at high intensity intervals only. Boxes extend to the first and third quartiles, and the horizontal line corresponds to the median. Whiskers extend to the largest and smallest value within 1.5 times the inter-quartile range. Dots correspond to values beyond the range of the whiskers (outliers). Regarding part B and D, max heart rate and max watt, respectively, were determined at the baseline watt-max test.

Table 4. Changes in study outcomes of six individuals with acquired brain injury receiving high intensity interval training

Outcome	Mean (SD)			Mean difference (SD)		Cohen’s d
	Pre	Post	FU ^a	Pre – Post	Pre – FU ^a	Pre–Post	Pre–FU ^a
MFI-20
General Fatigue	17.0 (2.2)	15.7 (2.4)	14.0 (3.3)	1.3 (2.4)	3.0 (2.1)	0.58	0.96
Reduced Motivation	10.0 (1.4)	7.0 (1.4)	7.6 (1.8)	3.0 (0.6)	2.8 (1.9)	2.12	1.82
Mental Fatigue	15.5 (3.2)	12.8 (4.2)	11.8 (3.4)	2.7 (2.5)	4.0 (1.9)	0.67	1.16
Reduced Activity	10.2 (3.1)	8.2 (4.0)	8.8 (2.2)	2.0 (2.1)	1.8 (1.8)	0.52	0.55
Physical Fatigue	13.3 (2.2)	9.3 (3.3)	10.6 (2.2)	4.0 (2.2)	3.2 (2.2)	1.26	1.51
Cardiorespiratory fitness
VO2max, l/min	2.11 (0.46)	2.64 (0.62)	2.34 (0.43)	−0.53 (0.29)	−0.24 (0.40)	−0.82	−0.68
Neuropsychological test
TMT-A, sec.	25.7 (8.8)	19.2 (6.6)	21.0 (8.3)	6.5 (4.2)	3.6 (3.5)	0.73	0.39
TMT-B, sec.	65.5 (22.4)	53.5 (16.0)	53.0 (20.6)	12.0 (16.9)	7.6 (8.6)	0.59	0.36
SDMT, score	50.8 (8.1)	55.5 (8.9)	55.4 (10.5)	−4.7 (2.6)	−4.4 (2.9)	−0.52	−0.39

Note. Pre = baseline; Post = post-intervention; FU = 6–8 months follow-up; MFI-20 = Multidimensional Fatigue Inventory; VO_2max = maximal oxygen uptake; TMT-A = Trail Making Test Part A; TMT-B = Trail Making Test Part B; SDMT = Symbol Digit Modalities Test.

^aAt follow-up, n = 5 on MFI-20 and neuropsychological test, and n = 4 on cardiorespiratory fitness. Cases with missing data was excluded by analysis.

Figure 3. Raw and mean scores on the multidimensional fatigue inventory.

Note. Straight lines indicate raw (transparent) and mean (bold) scores of participants on subscales of the Multidimensional Fatigue Inventory at i) baseline, ii) completion of High Intensity Interval Training (HIIT), and iii) 6–8 months after completion of HIIT. Dashed lines indicate mean scores of healthy individuals (N = 168, age range = 15–30 years), provided by Norup et al.¹³ One participant was lost to follow-up.

Norup A, Svendsen SW, Doser K, Ryttersgaard TO, Frandsen N, Gade L, Forchhammer HB. Prevalence and severity of fatigue in adolescents and young adults with acquired brain injury: a nationwide study. Neuropsychol Rehabil. 2019;29(7):1113–28. doi:https://doi.org/10.1080/09602011.2017.1371045.

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