Table 4.

Between-group difference (mean ± standard error) at (a) 4 months and (b) 12 months stratified by median age of the study population (≤ 45 years)

(a) 4 months	Older (> 45 years)					Younger (≤ 45 years)
	Δ	SE	95% CI	p	n	Δ	SE	95% CI	p	n
Work ability	− 0.34	0.41	− 1.16 to 0.48	0.41	53	0.61	0.37	− 0.12 to 1.33	0.10	58
Productivity	− 0.44	0.46	− 1.36 to 0.47	0.34	53	0.99	0.37	0.26 to 1.72	0.009	58
Need for recovery	− 0.4	5.3	− 11.0 to 10.3	0.95	52	− 9.8	6.0	− 21.7 to 2.1	0.11	58
Rating of perceived exertion	− 0.33	0.54	− 1.40 to 0.73	0.53	53	− 1.13	0.54	− 2.20 to – 0.07	0.04	58

(b) 12 months	Older (> 45 years)					Younger (≤ 45 years)
	Δ	SE	95% CI	p	n	Δ	SE	95% CI	p	n
Work ability	0.18	0.43	− 0.67 to 1.02	0.68	49	1.12	0.37	0.39 to 1.85	0.003	53
Productivity	− 0.92	0.57	− 2.04 to 0.21	0.11	49	1.27	0.38	0.52 to 2.03	0.001	53
Need for recovery	− 2.8	7.0	− 16.8 to 11.1	0.69	48	− 23.5	6.4	− 36.2 to − 10.8	0.0004	53
Rating of perceived exertion	− 0.22	0.56	− 1.33 to 0.88	0.69	49	− 0.26	0.53	− 1.31 to 0.79	0.63	53

Between-group 95% confidence interval and level of significance are reported. All outcomes are adjusted for baseline value of the respective outcome, age, sex (male), smoking status (never smoked and/or currently non-smoking), length of service and level of leisure time physical activity (< 2 h per week light activity)