Impact of (long) COVID on athletes’ performance: a prospective study in elite football players

Figures & data

Figure 1. Overview monitoring physical performance tests. ABD: abduction; ADD: adduction; CMJ: countermovement jump; YYIR: Yo-Yo Intermittent Recovery Test; m: metre.

Figure 2. The Yo-Yo intermittent recovery test.

Table 1. Participant demographics, injury and SARS-CoV-2 infections overview per team.

Subjects characteristics
	Team A (n = 32)	Team B (n = 30)	Team C (n = 22)
	Mean ± SD	Mean ± SD	Mean ± SD
Age (y)	23.72 ± 3.85	24.97 ± 4.34	25.50 ± 5.46
Height (m)	1.82 ± 0.68	1.83 ± 0.77	1.83 ± 0.59
Weight (kg)	77.85 ± 0.85	78.61 ± 0.83	77.90 ± 0.76
BMI (kg/m²)	23.40 ± 1.36	23.58 ± 1.53	23.31 ± 1.50
Games/ week (n)	1.70 ± 0.55	1.64 ± 0.56	1.23 ± 0.43
COVID-19 infections
	Count (%)	Count (%)	Count (%)
Number of infected players (n)	10	10	2
Symptomatic
Yes	8 (80)	8 (80)	2 (100)
No	2 (20)	2 (20)	0 (0)
Severity of the symptoms
Mild	1 (10)	5 (50)	1 (50)
Moderate	5 (50)	3 (30)	1 (50)
Severe	2 (20)	.	.
	Mean ± SD	Mean ± SD	Mean ± SD
Quarantine duration (days)	15.03 ± 7.06	9.00 ± 3.52	15.00 ± 0.0

Notes: Team A, B and C represent the three participating teams, pseudonymized. BMI: body mass index; SARS-CoV-2: Severe Acute Respiratory Syndrome Coronavirus 2; SD: standard deviation.

Table 2. The YYIR %HRmax in SARS-CoV-2 infected athletes over time.

					95% Confidence interval
		b	SE b	p Value	Lower bound	Upper bound
%HRmax at 3 min	Intercept	79.70	1.70	<.001	76.18	83.20
Halfway test	Pre COVID = ref category
	Post 1 COVID	3.91	2.11	.083	−0.57	8.40
	Post 2 COVID	−3.74	2.84	.205	−9.72	2.24
%HRmax at 6 min End of test	Intercept	84.91	1.19	<.001	82.43	87.39
	Pre COVID = ref category
	Post 1 COVID	4.47	1.87	.006	1.53	7.41
	Post 2 COVID	−1.95	1.38	.311	−5.91	2.00
%HRmax 1 min after test	Intercept	63.50	2.42	<.001	58.48	68.51
	Pre COVID = ref category
	Post 1 COVID	5.80	2.68	.045	0.14	11.46
	Post 2 COVID	0.78	3.64	.833	−6.87	8.42
%HRmax 2 min after test	Intercept	55.29	2.08	<.001	50.89	59.69
	Pre COVID = ref category
	Post 1 COVID	4.61	1.65	.013	1.10	8.12
	Post 2 COVID	2.16	2.26	.354	−2.64	6.96

Notes: p Values were obtained by means of mixed models analyses in the SARS-CoV-2 infected players and p-values <0.05 are in bold. %HRmax: percentage of maximal heart rate; b: %HRmax supplemented by the differences in %HRmax over time; Pre COVID: before the SARS-CoV-2 infection; Post 1 COVID: first post-infection test moment; Post 2 COVID: second post-infection test moment; Ref category: reference category; SARS-CoV-2: Severe Acute Respiratory Syndrome Coronavirus 2; SE b: the accompanying standard error; YYIR: Yo-Yo Intermittent Recovery test.

Table 3. The YYIR %HRmax in non-infected athletes over time.

					95% Confidence interval
		b	SE b	p Value	Lower bound	Upper bound
%HRmax at 3 min	Intercept	77.64	0.89	<.001	75.84	79.44
Halfway test	Pre = ref category
	Post	−2.54	1.11	.032	−4.85	−0.24
%HRmax at 6 min End of test	Intercept	85.20	0.73	<.001	83.73	86.67
	Pre = ref category
	Post	−1.76	0.53	.002	1.53	7.41
%HRmax 1 min after test	Intercept	64.59	1.26	<.001	62.06	67.12
	Pre = ref category
	Post	−3.47	1.08	.003	−5.65	−1.28
%HRmax 2 min after test	Intercept	53.67	1.68	<.001	50.25	57.09
	Pre = ref category
	Post	−5.29	1.66	.004	−8.75	−1.84

Notes: p Values were obtained by means of mixed models analyses in the non-infected players and p-values <0.05 are in bold. %HRmax: percentage of maximal heart rate; b: %HRmax supplemented by the differences in %HRmax over time; Pre: before the SARS-CoV-2 infection of the infected group; Pos: first test moment after the SARS-CoV-2 infection of the infected group; Ref category: reference category; SARS-CoV-2: Severe Acute Respiratory Syndrome Coronavirus 2; SE b is the accompanying standard error.

Figure 3. Mean and SD of %HRmax by YYIR timepoint according to COVID-19 status.

Table 4. Results of the YYIR %HRmax between formerly COVID-19 positive and non-infected players.

					95% Confidence Interval
		b	SE b	p Value	Lower Bound	Upper Bound
%HRmax at 3 min	Intercept	83.21	1.24	<.001	80.86	85.74
Halfway test	COVID infected = ref category
	Non-infected athletes	−8.14	1.53	<.001	−11.27	−5.02
%HRmax at 6 min End of test	Intercept	89.12	1.22	<.001	86.66	91.58
	COVID infected = ref category
	Non-infected athletes	−5.68	1.39	<.001	−8.48	−2.88
%HRmax 1 min after test	Intercept	69.41	2.26	<.001	64.86	73.96
	COVID infected = ref category
	Non-infected athletes	−8.30	2.58	.002	−13.48	−3.11
%HRmax 2 min after test	Intercept	58.93	1.86	<.001	55.09	62.78
	COVID infected = ref category
	Non-infected athletes	−10.56	2.28	<.001	−15.21	−5.90

Notes: p Values were obtained by means of mixed models analyses in all athletes and p-values <0.05 are in bold. %HRmax: percentage of maximal heart rate; b: %HRmax supplemented by the differences in %HRmax between groups; Ref category: reference category; SE b is the accompanying standard error.

Data availability statement

Data are available upon reasonable request. Requests for data sharing from appropriate researchers and entities will be considered on a case-by-case basis. Interested parties should contact Dr Wezenbeek ([email protected]).