Health football beats them all: subgroup analysis of the 3F (Fit&Fun with Football) study on white-coat hypertension, sustained hypertension, dippers, nondippers, and on pharmacologically un(treated) arterial hypertension

Abstract

Background: 

The 3F study (Fit&Fun with Football) demonstrated a significant reduction in blood pressure, antihypertensive medication, body weight, stress and depression through health football. Health football could be a popular tool to unleash the full preventive potential of physical activity. This work analyses the effect of health football on hypertensive subgroups: dipper, nondipper, white-coat hypertension (WCH), sustained hypertension, (un)treated hypertensive patients (UH, TH).

Methods: 

A prospective interventional study with 1-year follow-up. Football group (FG): n = 103, ‘health’-football training (1×/week, 90 min) led by licensed football coaches. Physical inactive, hypertensive patients older than 45 years were compared with a control group (CG) (n = 105). Subgroups were divided by ambulatory blood pressure monitoring (ABPM), casual blood pressure (CBP), medication schedule and compared by blood pressure (BP), laboratory results and weight.

Results: 

In all three subgroups (WCH vs. sustained hypertension, TH vs. UH, D vs. ND), health football reduced BP and weight significantly compared with the CG, and compared with the admission. An even greater effect in CBP was found in people with WCH than in sustained hypertension (FG: WCH: 141–127 mmHg, sustained Hypertension (SH): 142–132 mmHg; CG: WCH: 141–143 mmHg, SH: 140–141 mmHg). In contrast, the significant reduction in CBP and ABPM was comparable in treated and untreated patients, although antihypertensive drugs were reduced significantly more frequently in FG than in CG. BP reduction in nondippers and dippers was also comparable. In the nondipper group, nocturnal BP was significantly reduced in the FB (122.0–111.5 mmHg), but not in the CG or the dippers.

Conclusion: 

All evaluated football subgroups achieved a significant BP reduction (compared with CG). This applied to dipper, nondipper, (un)treated hypertension, WCH and SH. All mentioned subgroups displayed a clear benefit. The even greater reduction in BP in WCH demonstrates the importance of physical activity before the additional prescription of antihypertensive medications, underscoring the recommendations of the ESC and ISH in WCH.

INTRODUCTION

Physical activity improves almost all relevant cardiovascular and cerebrovascular risk factors (CVRF). These include arterial hypertension, dyslipidemia, diabetes mellitus, obesity, psychological stress as well as depression and nicotine weaning ^[1,2]. Still, the majority of Germans are not sufficiently physically active as medically recommended ^[3].

In addition, it is very challenging to motivate individuals who have been physically inactive for decades and have already developed a number of CVRF or have had a cardiovascular event in the past. Football remains to be the most popular sport in Europe with a great infrastructure that can reach people even in the smallest communities. Football, therefore, offers the ideal conditions to unfold the full preventive potential of physical activity, especially among risk groups. However, football has no relevance in cardiovascular prevention so far. This is mostly because of the lack of evidence of its beneficial effects as well as the high injury rate among players ^[4,5]. Therefore, a training format called Health Football was developed that is focused on improving fitness, health, without risking major injury.

This concept was evaluated in the prospective 3F-Study (Fit&Fun with Football) in a weekly health football training over 1 year in middle-aged hypertensive patients compared with a control group, who received standard care prevention recommendations. This study showed significant improvements regarding weight loss, reduction in antihypertensive medication and hypertension (casual and long-term blood pressure) in the football group (FG) but not in the control group (CG). The primary endpoints were published in the Journal of Hypertension^[6]. This subgroup analysis aims to evaluate the effects of health football on individuals with white-coat hypertension (WCH), dippers and nondippers as well as pharmacologically treated and untreated hypertension.

METHODS

Study design

The study was conducted as a prospective interventional study and took place in northwest Germany between 2019 and 2020. It analysed the influence of ‘health-football’ under the supervision of licensed football coaches on middle aged obese men suffering from arterial hypertension with the minimum age of 45 who have been physically inactive for several years. A comparison was made with a CG that received intensified written prevention recommendation based on European guidelines. The ‘health-football’ training took place among five football clubs with 20 participants each and was performed weekly for 90 min for a total of 14 months.

The primary objective of this study was to achieve a significant reduction of the casual blood pressure (CBP) or ambulatory blood pressure (ABPM) and a reduction in number or dosage of antihypertensive medication after 14 months in comparison to the CG.

The secondary study objectives were improvement in other CVRF (diabetes mellitus, smoking, weight, dyslipidaemia and occupational stress), change in cardiovascular medication, reduction in day and night blood pressure, blood pressure values and heart rate in ABPM. All primary study objectives were impressively achieved and have already been published ^[6]. The evaluation of the secondary study objectives is the aim of this evaluation.

The protocol was approved by the Ethics Committee of the Georg-August-University Göttingen and registered in the German Register of Clinical Trials (DRKS00017635).

First, second and last authors wrote the manuscript, the fourth author was responsible for the statistical analysis, all other authors participated in improving the manuscript. The decision to submit the manuscript for publication was made jointly by all authors, who also guaranteed the completeness and correctness of the data and the study conduct.

Recruitment

The 3F study is based on the ELITE Study (nutrition, lifestyle and individual information for the prevention of stroke, dementia and myocardial infarction). The aim of the ELITE study, itself a prospective cohort study, was to evaluate CVRF including psychosocial factors among over 5000 participants and to improve those through individualized written prevention recommendations based on a yearly follow-up. Study design and the most important data from the admission examinations have already been published ^[2,7–11]. Male hypertensive patients at least 45 years of age who had been inactive in physical activity for several years were filtered out of this database. Thus, 89 patients (FG) and 101 patients (CG) could be evaluated at the end of the study. The assignment to a group was random. The detailed methodology, recruitment with drop-outs and primary study results have already been published ^[6].

Health football

Health football is a new training concept devolved specifically for this study in cooperation with DFB (German Football Association)-licensed coaches. This new training entity aims to reduce the risk of injury, to focus on the fun aspect of physical activity and to allow each participant, regardless of ability, to have equal time with the ball. The training adapted to the needs of the risk patients. Tacklings as well as headers and high shooting were not allowed on the football field. The design of the football fields was also changed. Instead of two goals on the football field, four to six were present. In addition to the physical activity, cognitive training such as strategy planning and coordination was included into every training session. The DFB-licensed-coaches underwent an initial training themselves to adapt to the new concept. For sustainability reasons, the football teams were linked to local clubs so that training could continue after the end of the study. The ball used was a light ball provided by adidas (Team Junior 350). The activity on and off the pitch was monitored by a smart watch by Polar Ignite. Each Football club provided a defibrillator, which did not come to use during the training sessions.

Data collection and parameters

The data was collected through interviews and standardized questionnaires, and blood samples were taken by healthcare professionals. At baseline, blood pressure (BP) measurements (Microlife ‘WatchBP Office’ device, oscillometric measurement; Microlife, Widnau, Switzerland) were taken on both sides after 5 min of quiet sitting in three conventional measurements with a 1 min break between each measurement. A cuff was used to fit the arm circumference. The mean value of the arm with higher measurements was included in the evaluation. Furthermore, BP and weight were documented bevor each training session. In addition, BP was documented daily by the participants according to the above standards for 1 week per month (Beurer BM 27 upper arm blood pressure monitor). The 24-h long-term blood pressure measurements (SpaceLabs 90207; SpaceLabs, Snoqualmie, Washington, USA) were taken at the admission and end of the study in the FG and CG. Measurements were taken every 15 min during the day (between 0600 and 2200 h) and every 30 min at night (between 2200 and 0600 h). The participants were informed about behavior during the measurement, and a representative working day was chosen.

This resulted in the groups of dippers and nondippers. Participants were classified as dippers if they had a physiological nocturnal BP drop of at least 10% to less than 20% and as nondippers if they had a nocturnal blood pressure drop below less than 10% ^[12]. Patients with normotensive long-term BP measurements were classified as WCH patients, with average daily mean values less than 135/85 mmHg whereas the BP in the doctor's office was greater than 140/90 mmHg ^[13].

Statistics

The statistical analysis was carried out by IBM SPSS Statistics Software, version 26 (IBM, Armonk, New York, USA). Descriptive statistics were used to illustrate the data. The relationship between two categorical variables was determined by cross-tabulation and chi-square test such as McNemer test. To control for the assumed normal distribution of the data, the data were tested by the Kolmogorov–Smirnov test. The t test was used to compare two independent groups. Paired samples were assessed by the Wilcoxon test. The significance level of alpha = 0.05 was chosen for all statistical tests. The null hypothesis was thus rejected if there was a P value smaller than 0.05.

RESULTS

Table 1 illustrates the baseline and final weight, ABPM as well as the lipid profile of the both FG and CG, differentiated in sustained and WCH. The results of the ABPM are also illustrated in Table 1. Due to the definition of WCH, there were no significant differences among the FG and CG at admission. Individuals with sustained hypertension on the other hand showed significant BP reductions in the FG (Table 1). The body weight was generally higher among participants with sustained hypertension; however, both subgroups (WCH and sustained Hypertension (SH)) of the FG achieved a significant weight reduction whereas both CG showed a significant weight gain (Table 1). The laboratory results showed only slight changes over time (Table 1). The low-density lipoprotein (LDL)-cholesterol showed a significant drop among participants with WCH in the FG with an increase in high-density lipoprotein (HDL)-cholesterol. The FG with SH, however, showed only minor, nonsignificant changes. With consideration that the CGs showed an increase of statin use over time, the decrease of cholesterol and triglycerides were considered as pharmacological influence.

TABLE 1 - White-coat hypertension vs. sustained hypertension

	White coat hypertension						Sustained hypertension
	Football group			Control group			Football group			Control group
	Adm.	Final	Sign.	Adm.	Final	Sign.	Adm.	Final	Sign.	Adm.	Final	Sign.
Weight (in kg)	95.0	92.0a	<0.001	91.7	94.3a	<0.001	102.7	99.3a	<0.001	96.5	97.6a	<0.001
ABPM (in mmHg)
24-h sys.	119.4	119.0	0.811	119.1	122.3	0.237	130.3	121.9a	<0.001	130.6	132.4	0.405
Day sys.	124.3	124.0	0.856	127.3	126.7	0.943	135.0	126.2a	<0.001	135.6	136.1	0.603
Night sys.	107.9	108.8	0.827	109.1	113.9	0.119	118.7	112.9a	0.054	119.8	122.6	0.582
24-h dia.	74.1	74.9	0.616	74.0	76.3	0.512	80.6	75.3a	<0.001	80.2	80.7	0.908
Day dia.	78.2	78.4	0.481	77.7	79.7	0.745	84.6	79.2a	<0.001	84.0	84.1	0.538
Night dia.	66.9	67.6	0.239	66.3	70.1	0.25	72.5	67.2a	0.001	72.2	73.2	0.546
Blood results (in mg/dl)
Cholesterol	203.6	206.8	0.269	202.3	198.4	0.404	205.6	202.3	0.256	207.1	199.2a	0.046
LDL	142.1	135.5a	0.06	137.8	131.2	0.112	139.8	136.5	0.356	136.7	130.3a	0.036
HDL	46.5	49.6a	<0.001	52.1	51.3	0.476	50.5	52.8	0.027	50.6	51.6	0.075
Triglycerides	203.0	217.2	0.481	171.3	176.2	0.434	196.8	178.2	0.136	224.2	188.6a	0.018

ABPM, ambulatory blood pressure monitoring; Adm, admission; Dia, diastolic; HDL, high-density lipoprotein; LDL, low-density lipoprotein; Sys, systolic.

^aSignificant changes adm. vs. final.

Thirty-seven participants of the FG had WCH of which 15 were under antihypertensive treatment whereas 35 participants in the CG had WCH with 16 people being treated pharmacologically.

The remaining 52 participants in the FG had SH of which 38 were initially pharmacologically treated. In the control group remained 51 with SH of which 39 took antihypertensive medication.

The initial CBP of the participants with WCH did not differ from the participants with SH neither among the FG nor the control group. Both football groups (SH and WCH) showed a significant BP reduction while both CG showed an increase, although this was not significant.

Nevertheless, the most substantial BP drop was among the participants with WCH in the football group (Fig. 1) even under the consideration, that both football groups were considerably under less antihypertensive treatment in comparison to both control groups (Fig. 2).

FIGURE 1: Football group: casual blood pressure white-coat hypertension vs. sustained hypertension.

FIGURE 2: Control group: casual blood pressure white-coat hypertension vs. sustained hypertension.

Table 2 illustrates the comparison of treated and untreated arterial hypertension in regard to weight, ABPM, CBP and lipid profile. The comparison showed initially no significant differences except the body weight. Participants with treated hypertension had a higher BMI at admission than the untreated individuals. Both FGs showed a similar CBP and ABPM at admission and continued to show a significant and comparable decrease in each as well as in the body weight. In addition, the nocturnal BP was significantly reduced among the nontreated FG. On the other hand, both CGs showed an increase in body weight, CBP, and ABPM.

TABLE 2 - Treated vs. untreated arterial hypertension

	Treated arterial hypertension						Untreated arterial hypertension
	Football group			Control group			Football group			Control group
	Adm.	final	Sign.	Adm.	final	Sign.	Adm.	final	Sign.	Adm.	final	Sign.
Weight (in kg)	103.0	99.9a	<0.001	97.6	99.5a	<0.001	94.1	91.3a	<0.001	89.1	90.4a	0.005
BMI (kg/m2)	30.9	29.8a	<0.001	30.3	30.9a	<0.001	28.5	27.6a	<0.001	26.8	27.2a	0.004
Casual blood pressure (in mmHg)
Sys.	142.2	131.5a	<0.001	143.0	144.4	0.406	143.2	129.7a	<0.001	136.9	140.1	0.071
Dia.	87.0	81.4a	0.001	87.6	88.0	0.805	89.2	82.5a	0.001	88.1	88.5	0.79
ABPM (in mmHg)
24-h sys.	126.7	121.2a	0.001	128.0	129.4	0.283	124.2	120.1a	0.016	122.9	126.9	0.356
Day sys.	131.6	125.5a	<0.001	135.0	132.9	0.874	129.0	125.0a	0.025	127.7	131.3	0.408
Night sys.	113.7	112.7	0.792	117.1	119.4	0.308	115.3	107.3a	0.035	113.5	118.1	0.324
24-h dia,	78.0	74.9a	0.004	77.5	76.7	0.881	77.6	75.3a	0.007	78.8	80.7	0.451
Day dia.	82.2	78.4a	0.001	81.4	79.7	0.473	81.7	79.2a	0.01	82.5	84.1	0.587
Night dia.	70.5	67.6a	0.008	69.2	70.1	0.462	69.7	67.2a	0.019	71.6	73.2	0.358
Blood results (in mg/dl)
Cholesterol	198.8	197.8	0.734	197.5	190.4a	0.049	215.1	213.7	0.6	218.8	214.7	0.367
LDL	133.5	130.5	0.404	131.3	122.0a	0.01	152.0	144.6a	0.021	147.5	146.9	0.465
HDL	49.4	53.2a	<0.001	50.9	51.0	0.651	47.9	48.8	0.24	51.8	52.3	0.482
Triglycerides	198.4	187.8	0.553	202.1	187.2	0.237	206.5	204.9	0.931	203.7	177.0	0.355

ABPM, ambulatory blood pressure monitoring; Adm, admission; Dia, diastolic; HDL, high-density lipoprotein; LDL, low-density lipoprotein; Sys, systolic.

^aSignificant changes adm. vs. final.

Furthermore, the frequency of antihypertensive medication was significantly reduced among the football group, while the treated control group showed only minor changes.

At the final evaluation, 48 of the 53 initially treated participants in the FG remained on antihypertensive treatment, whereas 5 participants no longer required pharmacological treatment. The CG (treated hypertension) was able to reduce the number of treated participants by 1. All initially untreated participants in the football group remained untreated.

Among the treated football participants, a steep increase of HDL-cholesterol was noted while the overall cholesterol and LDL-cholesterol decreased. Similar results were seen in the CG. However, the use of statins was also higher among this group. The FG participants without antihypertensive treatment showed a decrease in the LDL-cholesterol while simultaneously taking less statins overall.

Initially, in total 10 participants among both FGs and nine individuals among both CGs were under statin therapy. Although there was no change within the FGs, both CGs showed a total increase from nine to 17 individuals under statin therapy.

Table 3 shows the comparison of dippers and nondippers. Similar results were found for the impact of health football on dippers and nondippers. The FGs again showed a significant reduction in regard to the body weight, CBP and ABPM. Both CGs showed a similar and significant increase in those categories. By definition, the nocturnal BP was higher among nondippers than among dippers. The FG dippers showed no significant changes in regards to nocturnal BP whereas in CG, a significant BP increase was noted. In the FG nondippers, in contrast, nocturnal BP decreased significantly, while almost no changes were found in CG.

TABLE 3 - Comparison of dippers and nondippers

	Dipper						Nondipper
	Football group			Control group			Football group			Control group
	Adm.	Final	Sign.	Adm.	Final	Sign.	Adm.	Final	Sign.	Adm.	Final	Sign.
Weight (in kg)	97.5	94.6a	<0.001	94.8	96.5a	0.001	101.6	98.4a	<0.001	95.0	96.8a	0.003
BMI (kg/m2)	29.6	28.7a	<0.001	29.1	29.6a	0.001	30.3	29.4a	<0.001	29.3	29.9a	0.003
Casual blood pressure (in mmHg)
Sys.	141.3	131.2a	<0.001	138.5	142.8a	0.005	143.9	130.2a	<0.001	143.3	141.5	0.406
Dia.	87.7	81.5a	<0.001	86.3	88.5	0.098	88.2	82.3a	0.01	88.2	87.3	0.204
ABPM (in mmHg)
24-h sys.	125.3	119.8a	0.001	125.5	127.9	0.156	126.5	121.9a	0.021	128.5	129.4	0.697
Day sys.	132.0	124.9a	<0.001	133.9	132.6	0.889	128.9	125.9	0.113	129.7	131.9	0.549
Night sys.	108.2	109.7	0.595	111.4	116.4a	0.028	122.0	111.5a	0.007	124.9	123.5	0.388
24-h dia,	77.5	74.5a	0.001	77.5	77.7	0.411	78.6	75.9a	0.025	78.6	79.0	0.428
Day dia.	82.7	78.6a	<0.001	82.0	81.5	0.751	81.1	79.1	0.088	81.1	81.2	0.28
Night dia.	67.7	66.2	0.097	67.7	70.3a	0.026	73.3	69.1a	0.001	73.3	72.8	0.19
Blood results (in mg/dl)
Cholesterol	206.5	202.0	0.251	204.2	197.5a	0.023	203.4	208.3	0.348	205.3	198.0	0.277
LDL	139.8	131.6a	0.025	136.3	129.0a	0.016	142.4	142.9	0.884	136.5	130.7	0.215
HDL	49.9	52.3a	0.002	50.4	50.5	0.68	47.5	50.6a	0.014	52.2	53.0	0.452
Triglycerides	207.5	199.2	0.61	211.3	191.2	0.212	191.7	191.5	0.855	194.1	168.1	0.213

ABPM, ambulatory blood pressure monitoring; Adm, admission; Dia, diastolic; HDL, high-density lipoprotein; LDL, low-density lipoprotein; Sys, systolic.

^aSignificant changes adm. vs. final.

The lipid profile improved in both the FG dippers and the CG dippers. However, as mentioned before, statins were taken more frequently by participants in the CG. HDL-cholesterol increased in both FG's.

DISCUSSION

In the 3F study, regular football training over 1 year led to significant reductions in blood pressure, body weight and antihypertensive medication in hypertensive men compared with a control group ^[6]. Interestingly, one 90 min training session per week was enough for this.

Untreated and antihypertensive-treated hypertensive patients were included. The inclusion was based on the results of the casual blood pressure measurement. Based on the protocol, patients with and without antihypertensive therapy, patients with dipping and nondipping and patients with WCH and sustained hypertension thus participated in the study. This subgroup analysis aimed to evaluate the effect of health football on different hypertensive groups. It was found that BP was significantly reduced in all football-subgroups compared with baseline and compared with the control group. This was true for treated and untreated patients, for dippers and nondippers and for patients with WCH or sustained hypertension. Thus, all hypertensive patients benefited from the football training.

The subgroup of patients with WCH included all participants with an increased CBP while the ABPM preserved normal blood pressure values. It, therefore, contained treated as well as untreated participants. WCH can be seen among patients treated with antihypertensive medication. It must then be asked whether therapy was started solely on the basis of CBP measurements in the practice or whether the start of therapy was based on manifest hypertension justified by self-measurements or ABPM. This study analyzed both, treated (FG, n = 15; CG, n = 16) as well as untreated (FG, n = 22; CG, n = 19) patients with WCH as a joined entity. A separate evaluation was because of the number of participants not feasible. The WCH football group showed a significant reduction with regard to the CBP in comparison to the SH football group while the control group showed no substantial changes for neither subgroup. Even though, both subgroups had similar BP values at baseline. Patients with sustained hypertension (FG and CG) displayed a significant higher body weight at admission. However, the more favorable BP reduction among patients with WCH showed no correlation to the baseline body weight. Both football subgroups displayed a comparable and significant BMI reduction while the control groups showed a body weight gain, which was more pronounced among patients with WCH.

Patients with WCH are more likely to develop sustained hypertension in comparison to the normotensive population. Studies such as the PAMELA study have linked WCH to a 2.5 times increased risk of progression to SH over the time course of 10 years ^[14]. Insufficient physical activity could increase the progression of WCH through weight gain, as observed in the control group. On the contrary, physical fitness has proven to delay it ^[15]. These facts underline the importance of ABPM for early detection and initiation of therapies with regard to lifestyle changes. International guidelines by American Heart Association (AHA) and European Society of Cardiology (ESC) have previously stated the necessity of nonpharmacological approaches prior to pharmacological therapy in regard to WCH unless end-organ damage has already manifested ^[16,17]. End-organ damage is more common in patients with WCH overall, as is increased mortality compared with normotensives ^[18–22].

The impressive blood pressure reduction through health football in our study in PH underlines the recommendations for more physical activity. However, in the PHYLLIS study, it was shown that drug therapy in PH also leads to a sustained reduction in blood pressure as in MH ^[23]. Although no ABPM measurements were carried out here. Furthermore, the PHARAO-study ^[24] involving ABPM was able to demonstrate the beneficial effect of antihypertensive therapy with ramipril among patients with high-normal blood pressure in comparison to a placebo group in which progression to sustained hypertension was significantly reduced. Furthermore, the PHARAO-study ^[24] involving ABPM was able to demonstrate the beneficial effect of antihypertensive therapy with ramipril among patients with high-normal blood pressure in comparison to a placebo group in which progression to sustained hypertension was significantly reduced. Even though patients with WCH demonstrated the most significant reduction in CBP measurements, the other subgroups showed significant improvements as well. Treated and untreated patients with arterial hypertension showed significant and yet comparable results. Both achieved BP and bodyweight reductions. Nevertheless, the significant reduction of antihypertensives in the treated FB group has to be taken into account, so that the BP-lowering effect might be underestimated. Naci et al.^[25] demonstrated that the antihypertensive effects of physical activity among pharmacologically treated patients were stronger compared with untreated individuals. Another meta-analysis by Saco-Ledo et al.^[26] showed comparable results. This could be because of synergistic effects of sport and antihypertensive therapy in combination. Salt loss through sweating could lead to an enhanced lowering of blood pressure, just as physical activity increases the effect of ACE inhibition, as shown by Maris et al.^[27]. Another study by Ramirez-Jimenez et al.^[28] demonstrated an enhanced effect of angiotensin receptor antagonists combined with physical activity. However, during the health football training sessions, no symptomatic hypotension cases were noted.

Regarding the subgroup dippers and nondippers, an insufficient nocturnal blood pressure drop or even increase has diagnostic, prognostic and therapeutic consequences. A pathological nocturnal blood pressure should always be further investigated to exclude an underlying treatable disease. Own studies have shown that about 70% of patients with secondary hypertension also had a disturbed day–night rhythm ^[29]. Chotruangapa et al., Cuspidi et al. and Salles et al. were able to point out the poor prognosis of nocturnal hypertension, especially associated with the reverse dipping phenomenon ^[12,30,31]. The Spanish Hygia study underlined the prognostic value of nocturnal blood pressure independently from ABPM. Especially for nondippers, taking an antihypertensive medication in the evening has often proven to be essential for blood pressure treatment ^[20]. Nevertheless, Mackenzie et al.^[32] recently demonstrated no difference on cardiovascular outcome between morning or evening antihypertensive medication in their TIME study. This study showed a comparable successful blood pressure reduction in all football participants, whereby no distinction was made between dippers and nondippers. The nondippers also succeeded in significantly lowering both systolic and diastolic nocturnal blood pressure. BMI also decreased significantly in both subgroups, whereas the control group experienced weight gain. We defined the nocturnal period as the time between 10 p.m. to 6 a.m. However, a limitation of the study was the lack of documentation of the exact sleeping time by some of the participants. The nocturnal blood pressure is related to the exact sleeping time ^[33,34] and, therefore, further evaluations could not be performed. We, therefore, adapted the current MY-3F (Fit&Fun with Football after Myocardial Infarction) study, which addresses health football in secondary prevention in patients after a previous myocardial infarction, to include ambulatory blood pressure monitoring in combination with sleep analysis. Improvement in terms of nocturnal blood pressure management is essential because of its poor prognosis. Studies by Ling et al.^[35], Ramirez-Jimenez et al.^[36] and Sherwood et al.^[37] were able to previously state the positive influence of physical activity on nocturnal blood pressure, especially through aerobic exercise and stress management.

In conclusion, this subgroup analysis aimed to evaluate the effect of health football on different hypertensive groups, and it showed that all evaluated subgroups achieved a significant blood pressure reduction in comparison to the control group. This, therefore, applied to dippers and nondipper, treated and untreated hypertension and especially patients with WCH. All mentioned subgroups displayed a clear benefit.

ACKNOWLEDGEMENTS

The study was supported by local sponsors, trainers and staff members to whom we would like to express our sincere thanks: Landkreis Cloppenburg, Deutscher Fußballbund (DFB), AOK Gesundheitskasse, Auto Thien Saterland, Bäckerei Behrens-Meyer, Big Dutchmann International GmbH, Bilfinger Ems GmbH, Biochem Zusatzstoffe Handels-und Produktionsgesellschaft mbH, Bley Haushaltswaren, Böckmann Center Lastrup, Brand Qualitätsfleisch GmbH & Co.KG, Maschinen- und Metallbau Claaßen, DiNo 1 GmbH, Dörffler, elektro-Koopmann GmbH, Fleming + Wendeln, Geflügelhof Meyer, Heidemark GmbH, Lüske Höltinghausen Gemüse- und Pflanzenhof, Paul Lüske GmbH, Mählmann – Gemüsebau, Miavit GmbH, Bernd Möllerhaus, Clemens Osterhus GmbH & Co KG, SK-Meat-Vertriebs GmbH, H.Piechota Kunstoffaufbereitung, Sanofi Aventis Deutschland Gmbh, Servier Deutschland GmbH, Sieverding Heizungs- und Sanitärtechnik GmbH, Sprehe Geflügel- und Tiefkühlfeinkost, Stadtmagazin Cloppenburg, Torfwerk Stadtsholt, Stevens Truthahn Delikatessen GmbH, Hans und Marlies Stock-Stiftung, Stottmann Einlagerungs GmbH, Suding Beton- und Kunstoffwerk GmbH, VR-Banken, Kurt Weigel GmbH, Wernsing Feinkost GmbH, Modehaus Werrelmann, Wessendorf Systembeschichtungen football-trainer: N. Anstatt, B. Diekmann, R. Ewen, J. Flaws, B. Garmann, J.-U. Klütz, A. Woloschin, staff: Marion Lammers, Sandra Garstecki, Tanja Abeln, Stefanie Schrapper.

Conflicts of interest

There are no conflicts of interest.