Preoperative community based functional high intensity interval training (f-HIIT) with high-risk patients opting for lumbar spinal fusion: a pilot study

Figures & data

Figure 1. Flowchart of measurement time points (diamonds) of trained and untrained patients opting for 1–3 level lumbar spinal fusion surgery. SRT: Steep Ramp Test; T: time point.

A flowchart describing the steps in patient selection between low-risk and high-risk patients and from the high-risk patients between untrained and trained patients. Thereafter, it shows the when measurements took place in the different subgroups respective to undergoing lumbar spinal fusion.

Figure 2. Flowchart of the in- and exclusion of patients. LSF: lumbar spinal fusion. *Outliers were defined as any value that is more than 1.5 IQR below the first quartile or above the third quartile.

A flowchart describing the number of inclusions and exclusions of patients at the different phases of the study and the reasons for exclusion. Eleven high-risk patients were included in the matched untrained group and 11 patients were included in the matched trained group.

Table 1. Baseline characteristics for high-risk and low-risk patients undergoing elective level one to three LSF.

	Total (n = 135)	Low-risk (n = 89)	High-risk (n = 46)	p Value difference high and low-risk group
Sex, n women (%)	84 (62.2)	45 (50.6)	39 (84.8)	<0.001^a
Age in years, mean (SD)	60.6 (11.7)	58.7 (11.1)	64.2 (5.0)	0.009^b
BMI, mean (SD)	26.8 (4.7)	25.9 (4.3)	28.7 (5.0)	<0.001^a
Smoking status, n smoker/ n observed^c (%)	44/127 (29.7)	29/84 (34.5)	7/43 (16.3)	0.032^a
ASA-score, n (%)				<0.001^a
ASA-1	29 (21.4)	25 (28.1)	4 (8.7)
ASA-2	85 (63.0)	56 (62.9)	29 (63.0)
ASA-3	21 (15.6)	8 (9.0)	13 (28.3)
Pain duration, n > 1 year/ n observed (%)	67/122 (49.6)	45/80 (50.6)	22/42 (52.4)	0.15^a
Surgery indication, n (%)				0.86^a
Spondylolisthesis	83 (61.5)	56 (62.9)	27 (58.7)
Degenerative disc disease	52 (38.5)	33 (37.1)	19 (41.3)
N levels fused, n (%)				0.28^a
1	98 (72.6)	67 (75.3)	31 (67.4)
2	32 (23.7)	20 (22.5)	12 (26.1)
3	5 (3.7)	2 (2.2)	3 (6.5)
Preoperative pain in 0–100, mean (SD), (n observed)	76.8 (18.6), (125)	74.9 (19.9), (82)	80.7 (15.2), (43)	0.15^a
Flexibility in cm, mean (SD), (n observed)	9.7 (11.4), (128)	8.9 (10.2), (87)	11.6 (13.5), (41)	0.36^a
Motor control 0–4, n (%)				0.011^a
0	2 (1.5)	1 (1.1)	1 (2.2)
1	7 (5.2)	3 (3.4)	4 (8.7)
2	18 (13.3)	8 (9.0)	10 (21.7)
3	55 (40.7)	37 (41.6)	18 (39.1)
4	53 (39.3)	40 (44.9)	13 (28.3)
Back muscle endurance strength in sec., mean (SD), (n observed)	35.4 (39.8), (91)	41.5 (42.5), (65)	20.5 (27.8), (26)	0.006^a
Max. back muscle extensor strength in % from norm, mean (SD), (n observed)	−12.8 (35.0), (108)	−8.7 (34.5), (76)	−22.5 (35.0), (32)	0.040^a
Estimated aerobic capacity, mean (SD)	2.8 (0.9)	3.2 (0.6)	1.8 (0.5)	<0.001^b
mILAS = 0 in days, mean (SD)	5.2 (2.6)	4.6 (1.6)	6.3 (3.8)	0.005^a
LOS in days, mean (SD)	7.2 (3.4)	6.7 (2.8)	8.2 (4.1)	0.021^a

^aMann–Whitney U test,

^bIndependent sample t-test.

^cNumber of observations within cohort if missing data was apparent.

ASA: American Society of Anesthesiologists score; cm: centimeters; sec.: seconds; max.: maximum; mILAS: modified Iowa Level of Assistance Score; LOS: length of stay.

Figure 3. (a–d) Per patient progression on: a) the 30 s Chair Stand Test, b) the 2 min Walk Test and c) the Timed Up and Go test between week 0 and 4 of training, and d) per patient progression on the Steep Ramp Test between week 0 of training and directly preoperatively.

Four line plots named A, B, C and D portraing the progession in physical fitness of eleven trained patients. Outcomes of the 30 seconds Chair Stand Test, the 2 Minute Walk Test and the Timed Up and Go test between week 0 and 4 of training, and per patient progression on the Steep Ramp Test between week 0 of training and directly postoperatively are plotted.

Figure 4. (a and b) A boxplot comparing the trained and untrained high-risk patients on postoperative: a) time to functional recovery and b) length of hospital stay.

Two sections each containing two boxplots showing the difference in distribution in trained and untrained patients on two outcomes, being time to functional recovery in days and length of hospital stay. The groups differ significantly on time to functional recovery but not on length of stay.

Table 2. Baseline characteristics for high-risk patients undergoing elective level one to three LSF.

	Total (n = 22)	Trained (n = 11)	Untrained (n = 11)	p Value difference between trained and matched untrained group
Sex (n, women, %)	17, 77.30	8, 72.70	9, 81.82	0.619^a
Age in years (mean ± SD)	70.14 ± 9.260	71.45 ± 9.790	68.82 ± 8.970	0.469^a
Preoperative pain in 0–100 VAS score (mean ± SD)	77.50 ± 16.02	71.82 ± 15.37	83.18 ± 15.21	0.106^a
Smoking status (n, smoker, %)	2, 9.090	1, 9.090	1, 9.090	1.000^a
ASA-score
ASA-1 (n, %)	0, 0	0, 0	0, 0	^b
ASA-2 (n, %)	13, 59.10	7, 63.60	5, 45.45	1.000^a
ASA-3 (n, %)	9, 40.90	4, 36.40	6, 54.54	1.000^a

Comparison between the trained and untrained group.

SD: standard deviation; ASA-score: American Society of Anesthesiologists-Score.

^ap-value based on trained and untrained group measured with Mann–Whitney U test.

^bMann–Whitney U test cannot be performed on empty groups.

Figure 5. Effect of implementation of preoperative f-HIIT program on time to functional recovery (in days) in the matched high-risk population (n = 22).

A combined line scatter plot, plotting the average time to functional recovery over time before and after implementation of the functional high intensity training programme. A decrease in time to functional recovery can be seen directly after implementation of the training programme.

Figure 6. Effect of implementation of preoperative f-HIIT program on length of hospital stay in the matched high-risk population (n = 22).

A combined line scatter plot, plotting the average length of hospital stay over time before and after implementation of the functional high intensity training programme. A decrease in time to functional recovery can be seen directly after implementation of the training programme.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author, EJ. The data are not publicly available due to restrictions e.g., their containing information that could compromise the privacy of research participants.