# Change in Physical Fitness due to the COVID-19 Pandemic Lockdown in French Adolescents: A comparison between two independent large samples from Diagnoform battery

Laurent Beghin, David Thivel, Jean-Benoit Baudelet, Thibault Deschamps, Hervé Ovigneur, Jeremy Vanhelst

<figure><img src="image_1.png" /></figure>

## To cite this version:

Laurent Beghin, David Thivel, Jean-Benoit Baudelet, Thibault Deschamps, Hervé Ovigneur, et al. Change in Physical Fitness due to the COVID-19 Pandemic Lockdown in French Adolescents: A comparison between two independent large samples from Diagnoform battery. European Journal of Pediatrics, 2022, European Journal of Pediatrics, 181 (11), pp.3955-3963. 10.1007/s00431-022-04610-9. hal-04482326

HAL Id: hal-04482326

https://lilloa.hal.science/hal-04482326v1

Submitted on 10 Sep 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
Change in Physical Fitness due to the COVID-19 Pandemic Lockdown in French Adolescents: A
comparison between two independent large samples from Diagnoform battery.

1 Laurent Béghin¹, David Thivel², Jean-Benoît Baudelet³, Thibault Deschamps⁴, Hervé Ovigneur⁴, Jérémy

2 Vanhelst⁵

3

4 ¹Univ. Lille, Inserm, CHU Lille, U1286 - INFINITE - Institute for Translational Research in Inflammation, F-

5 59000 Lille, France

6 ²Université Clermont Auvergne, CRNH, AME2P, F-63000, Clermont-Ferrand, France. "Health in Motion"

7 International Research Chair, UCA foundation, France.

8 ³Univ. Lille, CHU Lille, Congenital & Pediatric Heart Unit, Institut Cœur Poumon, F-59000 Lille, France

9 ⁴IRFO, Diagnoform, F-59139 Wattignies, France

10 5 Sorbonne Paris Nord University, Inserm U1153, Inrae U1125, Cnam, Nutritional Epidemiology Research

11 Team (EREN), Centre of Research in Epidemiology and Statistics - University of Paris Cité (CRESS), Bobigny,
12 France.

13

14

15

16 **Corresponding author information:**

17 Jérémy Vanhelst

18 Sorbonne Paris Nord University

19 E-mail: jeremy.vanhelst@hotmail.fr
**Background:** Numerous studies reported a significant decline in physical activity level in adolescents as a result of the COVID-19 lockdown. Physical fitness is recognized as a powerful marker of health in youth. The aim of this study was to evaluate the impact of the COVID-19 Pandemic Lockdown on health-related physical fitness in French adolescents.

**Methods:** Two cross-sectional studies were performed comparing two different groups of French adolescents, before (sample 1) and after the first lockdown (sample 2). A total of 1231 adolescents (aged to 16.5 ± 1.5 years) participated in the two cross-sectional studies. Complete data for physical fitness and anthropometrics data were obtained.

**Results:** Adolescents from sample 2 showed lower physical fitness levels compared to adolescents from sample 1. Regarding physical fitness for boys and girls, physical fitness levels were significantly lower in both sex between adolescents from the sample 1 and adolescents from the sample 2, except for cardiorespiratory fitness and flexibility for boys and girls, respectively. The Physical fitness global score were also significantly lower between adolescents from the sample 1 and 2 for boys (-9.8%, p <0.01) and girls (-16,2%; p <0.01), respectively. Overall, the higher difference was found for performance in the speed body displacement test (-30%). A difference of 12,8% and 25% were observed for boys and girls, respectively.

**Conclusions:** COVID-19- Pandemic Lockdown had a negative impact on physical fitness in French youth. This study highlight the need to develop, in a near future, prevention programmes in order to improve the physical fitness in youth.

**Keywords:** Health crisis, youth, Health.

28

29

30

31

32

33

34
35 INTRODUCTION

36 Physical fitness is now widely recognized as a powerful marker of health in children and adolescents [1]. Health-
37 related physical fitness refers to the ability of your body systems to work together efficiently to allow you to be
38 healthy and perform activities of daily living [2]. Health-related physical fitness includes several components
39 such as cardiorespiratory fitness (CRF), musculoskeletal fitness (including muscular strength and endurance,
40 flexibility) and motor fitness [3]. In addition, body composition may be also included in health-related physical
41 fitness components [3]. Health-related physical fitness is associated to multiple health benefits, such as a low
42 risk to develop chronic diseases and premature death [1]. Recently, two systematic reviews and meta-analysis
43 showed the evidence linking both CRF and muscular strength in children and adolescents with the health status
44 later in life [4-5]. Authors showed that low muscular strength and CRF in adolescence are strongly associated
45 with risk factors for major causes of death in adulthood [4-5]. As shown in these two systematic reviews, CRF is
46 the most studied with strong evidence on health-related associations. A need to assess regularly this component
47 in youth is well established and underlined by the American heart Association [6].

48 In December 2019, a beginning a global pandemic emerged following an abnormal increase of viral pneumonia
49 in Wuhan. In March 2020, the World health Organization (WHO) announced a novel disease named Covid-19,
50 which is caused by the SARS-CoV-2 virus and became a worldwide pandemic. Consequently, governments took
51 several restrictions measures, including lockdown, who affected significantly daily physical activity behaviors.
52 In France, the first lockdown began from March 17th 2020 until May 11th 2020, i.e 55 days. During this
53 lockdown, all schools were closed while the school environment for children and adolescent is crucial to be more
54 physically active and to achieve meet physical activity guidelines [7-9].

55 Physical inactivity and sedentary behaviors have adverse consequences on physical fitness levels [10]. Many
56 research studies from different countries showed a worrying decrease of physical activity levels (PAL),
57 associated to a dramatic increase of time spent in sedentary behaviors during and after lockdown [11-12].
58 Authors constated that social context, parental education level, environment and physical characteristics are
59 factors having an impact on the percentage of decrease in PAL during lockdown [13-16]. While a substantial
60 decline in physical fitness levels adolescents was already found since many decades, this public health crisis
61 might therefore accentuate this worsening trend [17-18]. Many studies performed in European and American
62 countries confirms this trend. Overall, authors showed school-aged boys and girls exhibited significant physical
63 fitness performance losses after the successive lockdowns due to coronavirus disease period [19-27]. In France,
64 data on health-related physical fitness during this period are scarce and limited to children population [24].
Authors showed a significant decrease on physical fitness and motor fitness performances [24]. Main limits of this study are the low sample size (n=106 and 100 before and after confinements, respectively), exclusively in young children. Consequently, these limits arouse a particular interest to examine the impact of public health crisis in a large sample including adolescent population.

In this context, we hypothesize that the first lockdown had a negative impact on health-related physical fitness in French adolescents. Using data from two independent large samples, the aim of this study was to examine the impact of COVID-19 Pandemic Lockdown on health-related physical fitness in French adolescents.

## METHODS

### Participants

This study is part of the French health Diagnoform® programme (https://irfo.fr/) assessing physical fitness levels in French population from the age of 5 years. A cross-sectional design was used in order to contrast health-related physical fitness data of two samples of adolescents, evaluated before and after the lockdown in France.

For the present analysis, two cross-sectional studies were performed comparing two different groups of French adolescent students, who studied at the same school at two different school years (before and after the first lockdown, i.e september 2020 and September 2021).

A total of 1231 adolescents participated in the two independent large samples. Complete data for physical fitness and anthropometrics data were obtained for all participants. Before and after lockdown, 532 adolescents (318 boys, 214 girls) and 699 adolescents (325 boys, 374 girls) participated, respectively. Anthropometric characteristics and physical fitness were measured.

All data obtained from the organizer “Institut des Rencontres de la FOrme” of the event were anonymized, and declared and approved by the Commission Nationale de l'Informatique et des Libertés (National Commission on Informatics and Liberty). The assessment was explained to both adolescent and their parents, after which the children or their parents could accept or decline record anonymously their information technology data. Data were recorded by the organizer in an electronic data system. An audit of the complete dataset was performed, and aberrant data were excluded. As this research was not performed to improve biological or medical Human knowledge, this present study is not considered as clinical research according to French regulatory requirement (“Jardé” law). In this context, this study does not need any approval from an ethical committee [28].

### Anthropometric characteristics
Body weight was measured with the participant wearing light clothes and without shoes to the nearest 0.1 kg using an electronic scale (Seca, Hamburg, Germany). Height was measured without shoes to the nearest 0.1 cm using a standard physician's scale (Seca, Hamburg, Germany). Body Mass Index was calculated as weight/height² (kg/m²). Normal weight, overweight and obesity were assessed using specific thresholds according to WHO classification [29]. These international cut-offs are defined by values of BMI at age 18: BMI 18.5 normal weight, 25 (overweight) and 30 (obesity).

## Physical fitness

Health-related physical fitness procedures have been described below and its reliability and validity indicated, as previously published [30-32].

Cardiorespiratory Fitness (CRF) was measured by a 20-meter shuttle run-walk test during 6 min. This test has been validated against the 20-m shuttle run reference test from Leger et al (1988) (r = 0.78; P = 0.001) and showed a good reliability (0.84) [30]. Adolescents were instructed to run and walk as far as possible between two lines located 20 m apart during 6 min. The adolescent ran as quickly as possible from the starting line to the other line and returned to the starting line at a fast walking pace, crossing each line with at least one foot throughout the complete test. The test began on the whistle and was concluded after 6 min. The distance covered by the adolescent was recorded and was expressed in meter (m).

Lower Explosive strength (LES) was assessed by the standing broad jump test. This test showed a good reliability (0.84) [30]. From a starting position immediately behind a line, standing with the feet approximately shoulder width apart, adolescent jumped as far as possible with their feet together. The result was recorded in cm. A nonslip hard surface, chalk and a tape measure were used to perform the test.

Speed/agility (SA) was assessed by the 4 × 10 m shuttle run test. An excellent reliability was found for the 4x10m shuttle run in adolescent (0.90) [30]. Two parallel lines were drawn on the floor 10 m apart. The adolescent was instructed to run as fast as possible from the starting line to the second line and return, crossing each line with at least one foot every time. The test covered a total distance of 40 m (4 x 10 m). Test time ended when the adolescent crossed (again, keep verb tenses consistent) the end line with one foot. Time was recorded using a standard stop watch.
125

126

*Upper muscular strength and endurance (UMSE)* was assessed by the pushup test with knees on the ground. A good reliability was found for this test (0.81) [30]. Before the beginning of this test, participants did some light warm-up of arms and shoulders. Participants were positioned prone with hands shoulder width apart with the trunk held in a rigid, straight position. Participants began in the “up” position with their elbows fully extended.

127

128

129

130

When descending the body toward the ground adolescents flexed their elbows until the upper arm was parallel to the testing surface. They were instructed to limit head and trunk motion, and to perform as many push-ups as they can without break. No limit of time was defined. The result of the test was expressed in number of push’ups seconds (n).

131

132

133

134

135

*Lower muscular strength and endurance (LMSE)* was assessed by the five consecutive long jump. The reliability for this test was excellent (0.90) [30]. From a starting position immediately behind a line, standing with the feet approximately shoulder width apart, adolescent jumped five times consecutively (without break) as far as possible with their feet together. A nonslip hard surface, chalk and a tape measure were used to perform the test. The result was recorded in cm.

136

137

138

139

140

141

*Speed Body Displacement (SBD)* was assessed by a 30-m speed test. This test showed a good reliability (0.85) [30]. This test was performed by running as fast as possible for 20 m. The adolescent stood still in a comfortable position, feet behind the starting line, with no rocking movements. The test began on the whistle and was concluded when the adolescent crossed the finish line. Time was recorded using a standard stopwatch. The result of the test was expressed in seconds (sec).

142

143

144

145

146

147

*Coordination* was assessed by the five consecutive strides test. This test showed also an excellent reliability (0.90) [30]. The adolescent stood still in a comfortable position, feet behind the starting line, with no rocking movements. Adolescent performed five consecutive strides as far as possible. A nonslip hard surface, chalk and a tape measure were used to perform the test. The result was recorded in cm.

148

149

150

151

152

*Flexibility* was assessed by a test measuring leniency and the capability to reach down as far as possible. An excellent reliability was found (0.91) [30]. From a standing position, with both legs straight and feet together, the participant flexed their trunk and reached down as far as possible with their hands. Participant had to maintain

153

154
155

the position for 3 *sec*. Results of this test were indexed: a score of 5 for placing the hands flat on the ground; 4 for fingers touching the ground; 3 for fingers reaching the ankle; 2 for fingers reaching the tibia; and 1 for fingers/hands reaching the knees.

156

157

158

159

An individual global physical fitness score, called Quotient of Physical Fitness (QPF), was calculated. For this, absolute value obtained for each test was transformed to a normalized value from 1 (poor) to 20 (excellent). The mean of the normalized values for each test was computed to obtain the QPF expressed in "percentage".

160

161

162

163

## Statistical analysis

164

Continuous variables were expressed as means (standard deviation, SD) and categorical variables were expressed as numbers (percentage). Physical fitness components were described according to gender and time of assessment (pre and post lockdown samples). We assessed the difference between physical fitness tests performed in pre lockdown and post lockdown samples 2 using an independent t-test for continuous data, and chi2 test for categorical data. Values of *p* < 0.05 were considered statistically significant. All analyses were computed using R software (version 4.2.0).

165

166

167

168

169

170

## RESULTS

171

Table 1 shows the characteristics of the study population of adolescents from pre and post lockdown samples. No meaningful difference in anthropometrics characteristics was found between two samples.

172

173

Physical fitness levels according to sex among pre and post lockdown samples are described in Table 2 and Figure 1. In two independent samples, physical fitness was better in boys than in girls, except for the flexibility test. Overall, significant differences were found between two samples for each physical fitness components.

174

175

176

Adolescents from sample 2 (after the first lockdown) showed lower physical fitness levels compared to adolescents from sample 1. Regarding physical fitness for boys and girls, physical fitness levels were significantly lower in both sex between adolescents from the pre lockdown sample and adolescents from the post lockdown sample, except for cardiorespiratory fitness and flexibility for boys and girls, respectively. In boys, the performance of the cardiorespiratory fitness test was found to be significantly better for adolescents from post lockdown sample compared those from pre lockdown sample (579.9 ± 149.9 vs. 575.6 ± 98.0; *p* < 0.01). A similar trend was also found in adolescents girls for the flexibility test. In addition, and naturally in front of previous results mentioned above, the physical fitness global score (expressed in percentage) was also

177

178

179

180

181

182

183
significantly lower between adolescents from the pre and post lockdown samples for boys (57.8 ± 12.6 vs 52.2 ± 14.5; -9.8%, p <0.01) and girls (34.9 ± 10.8 vs 29.1 ± 11.1; -16.2%; p <0.01), respectively. Adolescents' girls have had a difference more important of their global score physical fitness levels (-16.2%) compared to adolescents boys (-9.8%).

Figure 2 showed difference in performance for each physical fitness tests between pre and post lockdown samples. Only the percentage difference of cardiorespiratory fitness in boys is positive, but remains low (+0.7%). Overall, the higher difference was found for performance in the speed body displacement test (-30%). A difference of 12.8% and 25% were observed for boys and girls, respectively. In contrast, the weaker change in overall was found in cardiorespiratory fitness results (-4.2%). The most slight difference for girls was to -4.8% in cardiorespiratory fitness level, and -3.9% for boys in performance for upper body muscular strength and endurance.

## DISCUSSION

The aim of this study was to assess, for the first time, the impact of the lockdown on the physical fitness levels in French adolescents.

The first main result from our study showed that both boys and girls had lower performance to physical fitness tests after the first covid-19 lockdown, expect for CRF in boys adolescent. Therefore, our initial study hypothesis is accepted. Our results are in agreement with a precedent study performed in French younger children [24]. Authors showed both muscular strength (upper and lower) and cardiorespiratory fitness were significantly reduced among 3rd- and 4th-grade children after the COVID-19 lockdown period compared with pre-pandemic performances [24]. Similar results were also found in adolescence population across many countries [19,23,25-27]. Our result is definitely not surprising in light of major movement restrictions involved by the French government during the pandemic situation in France. The decline of health-related physical fitness may be attributed to change lifestyle behaviors, i.e a decrease of physical activity levels, a sedentariness rising and unhealthy dietary intake. As previously described, schools, sports clubs and associations have closed during the lockdown inducing a decrease of opportunity to be physically active. Studies showed that school environment (recess, physical education lessons, commuting home to school) was favorable to be active and meet the WHO recommended physical activity guidelines [8, 33-34]. In addition, leisure-time out-of-school hours is used
212 mainly for sedentary activities [8]. Several studies in Europe confirmed these facts reporting a reduced physical activity level and increased sedentary behaviors in adolescents during lockdown period [35-37].
213

214 Another outcome found from our study was to note more evident global difference between pre and post lockdown in girls compared to boys. Expect to lower muscular strength and endurance test, girls had greater 215 difference between before and after first lockdown in physical fitness performance compared to boys 216 adolescents. Our results are contradictory to those previous studies in European adolescents [23, 25]. Sunda et al 217 (2022) showed a greater impairment in 600 m run and sit-up performance in Croatian boys than in girls after two 218 months of lockdown [25]. Tsoukos et al (2022) reported also a greater reduction in performance in flexibility, 219 505 agility and 30 m sprint tests in Greek boys compared to girls after 5-month lockdown [23]. We have no clear 220 explanation for this difference between our findings and those found in previous studies. Authors explained their 221 difference found lower in girls by the possibly greater decrease in physical activity in boys than in girls. 222 However, recent studies assessing changes in physical activity patterns due to lockdown showed that there was 223 no difference in decrease between girls and boys adolescents [25,37]. A possible explanation in the sex 224 difference in our study might be due the motivation to practice physical activity during the pandemic period. 225 Lack of willpower is reported as a main barrier in girls to perform exercise [38]. However, since we did not 226 assess physical activity patterns in the present study, we cannot speculate more about their roles in explaining a 227 greater physical fitness levels impairment in girls compared to boys adolescents and should deserve further 228 studies. 229

230 Lastly, our study revealed no consequences of the COVID-19 pandemic and imposed lockdown on the 231 anthropometric data in French adolescents. Sunda et al (2022) found similar results in their Croatian cohorts 232 [25]. To explain these results, authors have underlighted that adolescence is a life period very dynamic and 233 characterized by rapid changes in body composition (weight, height) and the availability of food and nutritional 234 habits, which are major determinants of growth, have not changed dramatically during the pandemic [25]. 235 However, an Italian study showed that children and adolescents confined due to Covid-19 pandemic showed 236 higher unhealthy foods, such as red meat, potato chip, and sugary drink consumption [39]. Our finding might be 237 attributed rather to the duration of movement restriction and lockdowns, not long enough to see a change in 238 anthropometric characteristics. Indeed, weight gain is caused by the combination of a less active lifestyle, 239 including sedentary behaviors, and a failure to reduce energy intake to match the reduced total energy 240 expenditure arising from reduced physical activity over a prolonged period of time. Our data concern only the
241 impact of the first lockdown, including 55 days. By consequent, this period seems too short to observe changes
242 in body composition unlike to physical fitness where short term physical inactivity (less than 4 weeks) have
243 already an impact [40].

244 Previous studies shows that the COVID-19 is associated with direct adverse health consequences in short and
245 long term [41]. Results from our study shows also an indirect impact on the health. Indeed, lockdown periods
246 have decreased in performances of physical fitness tests in youth whereas a poor physical fitness level in
247 adolescence is strongly associated with all-cause mortality and cardiovascular- and cancer-specific mortality in
248 later life [4-5]. Recently, data from a large prospective register have also showed linking physical fitness at a
249 young age is associated with severity of COVID-19 many years later [42]. In order to counteract the detrimental
250 effects of the COVID-19 disease, his multiples lockdown and social distancing imposed on physical fitness
251 levels among adolescents, there is a need to develop preventive strategies. Developing online intervention
252 programs of physical activity might be also a relevant strategy whether further mitigation would be taken.
253 Indeed, many studies showed that a remote physical education intervention maintained or even increased
254 physical fitness levels in children and adolescents [43-45].

255 Findings from our study brings first data on the health-related physical fitness consequences due to lockdown in
256 French adolescents. However, some limitations have to be considered. The main limitation is the design of this
257 study (cross-sectional design). Indeed, since the lockdown was unexpected, a longitudinal study was not
258 possible. However, we were able to assess physical fitness across two cross-sectional studies in adolescents
259 studying in the same school (i.e, same region and city in North of France). In light of this first limitation, our two
260 studies cohort are not representative of the French adolescent populations. Lastly, we did not collect several
261 qualitative and quantitative data, such as parents' education level, socioeconomic status or daily physical
262 activity, which have effects on health-related physical fitness in adolescents.

263 Findings of this present study demonstrate the negative impact of COVID-19- Pandemic Lockdown on health-
264 related physical fitness in French adolescents. After this public health crisis, still current, public health policies
265 must continue to promote a healthy lifestyle (dietary intake and physical activity) in youth in order to counterpart
266 adverse health consequences of these consecutives lockdown. Moreover, teachers and school policies should
267 include specific and adequate PA programs adapted to the age to reduce the risk of decrease of physical fitness
268 level when possible movement restrictions periods could occur. Further studies on the effects of the second and
269 third lockdown in France are warranted and expected. In addition, future studies should be performed across
270 several years in order to assess the impact of this health crisis on physical fitness among adolescents in a long-

271 term.

272

273

274

275

276

277
278 REFERENCES

279 1. Ortega FB, Ruiz JR, Castillo MJ, Sjöström M (2008) Physical fitness in childhood and adolescence: a powerful marker of health. Int J Obes (Lond) 32:1-11. doi: 10.1038/sj.ijo.0803774.

281
282 2. Caspersen CJ, Powell KE, Christenson GM (1985) Physical activity, exercise, and physical fitness: definitions and distinctions for health-related research. Public Health Rep 100:126-31.

284
285 3. Ruiz JR, Castro-Piñero J, Artero EG, Ortega FB, Sjöström M, Suni J, Castillo MJ (2009) Predictive validity of health-related fitness in youth: a systematic review. Br J Sports Med 43:909-23. doi: 10.1136/bjsm.2008.056499.

287
288 4. García-Hermoso A, Ramírez-Vélez R, García-Alonso Y, Alonso-Martínez AM, Izquierdo M (2020) Association of Cardiorespiratory Fitness Levels During Youth With Health Risk Later in Life: A Systematic Review and Meta-analysis. JAMA Pediatr 174:952-960. doi: 10.1001/jamapediatrics.2020.2400.

291
292 5. García-Hermoso A, Ramírez-Campillo R, Izquierdo M (2019) Is Muscular Fitness Associated with Future Health Benefits in Children and Adolescents? A Systematic Review and Meta-Analysis of Longitudinal Studies. Sports Med 49:1079-1094. doi: 10.1007/s40279-019-01098-6.

295
296 6. Raghuveer G, Hartz J, Lubans DR, Takken T, Wiltz JL, Mietus-Snyder M, Perak AM, Baker-Smith C, Pietris N, Edwards NM; American Heart Association Young Hearts Athero, Hypertension and Obesity in the Young Committee of the Council on Lifelong Congenital Heart Disease and Heart Health in the Young (2020) Cardiorespiratory Fitness in Youth: An Important Marker of Health: A Scientific Statement From the American Heart Association. Circulation. 2020 Aug 18;142(7):e101-e118. doi: 10.1161/CIR.0000000000000866.

301
302 7. Ridgers ND, Salmon J, Parrish AM, Stanley RM, Okely AD (2012) Physical activity during school recess: a systematic review. Am J Prev Med 43:320-8. doi: 10.1016/j.amepre.2012.05.019.

304
305 8. Vanhelst J, Béghin L, Duhamel A, De Henauw S, Molnar D, Vicente-Rodriguez G, Manios Y, Widhalm K, Kersting M, Polito A, Ruiz JR, Moreno LA, Gottrand F (2017) Relationship between school rhythm and physical
307

activity in adolescents: the HELENA study. J Sports Sci. 2017 Aug;35(16):1666-1673. doi:
10.1080/02640414.2016.1229013.

308

309

310

9. Loureiro N, Marques A, Loureiro V, de Matos MG (2021) Active Transportation to School. Utopia or a Strategy for a Healthy Life in Adolescence. Int J Environ Res Public Health 18:4503. doi: 10.3390/ijerph18094503.

311

312

313

314

10. Mateo-Orcajada A, González-Gálvez N, Abenza-Cano L, Vaquero-Cristóbal (2022) Differences in Physical Fitness and Body Composition Between Active and Sedentary Adolescents: A Systematic Review and Meta-Analysis. J Youth Adolesc 51:177-192. doi: 10.1007/s10964-021-01552-7.

315

316

317

318

11. Ganzar LA, Salvo D, Burford K, Zhang Y, Kohl HW 3rd, Hoelscher DM (2022) Longitudinal changes in objectively-measured physical activity and sedentary time among school-age children in Central Texas, US during the COVID-19 pandemic. Int J Behav Nutr Phys Act 19: 56. doi: 10.1186/s12966-022-01299-9.

319

320

321

322

12. Neville RD, Lakes KD, Hopkins WG, Tarantino G, Draper CE, Beck R, Madigan S (2022) Global Changes in Child and Adolescent Physical Activity During the COVID-19 Pandemic: A Systematic Review and Meta-analysis. JAMA Pediatr 11:e222313. doi: 10.1001/jamapediatrics.2022.2313.

323

324

325

326

13. Ng K, Cooper J, McHale F, Clifford J, Woods C (2020) Barriers and facilitators to changes in adolescent physical activity during COVID-19. BMJ Open Sport Exerc Med 6: e000919. doi: 10.1136/bmjsem-2020-000919.

327

328

329

330

14. Moore SA, Faulkner G, Rhodes RE, Brussoni M, Chulak-Bozzer T, Ferguson LJ, Mitra R, O'Reilly N, Spence JC, Vanderloo LM, Tremblay MS (2020) Impact of the COVID-19 virus outbreak on movement and play behaviours of Canadian children and youth: a national survey. Int J Behav Nutr Phys Act 17:85. doi: 10.1186/s12966-020-00987-8.

331

332

333

334
335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

15. Zhang X, Zhu W, Kang S, Qiu L, Lu Z, Sun Y (2020) Association between Physical Activity and Mood States of Children and Adolescents in Social Isolation during the COVID-19 Epidemic. Int J Environ Res Public Health 17: 7666. doi: 10.3390/ijerph17207666.

16. Guerrero MD, Vanderloo LM, Rhodes RE, Faulkner G, Moore SA, Tremblay MS (2020) Canadian children's and youth's adherence to the 24-h movement guidelines during the COVID-19 pandemic: A decision tree analysis. J Sport Health Sci 9: 313-321. doi: 10.1016/j.jshs.2020.06.005.

17. Tomkinson GR, Lang JJ, Tremblay MS (2019) Temporal trends in the cardiorespiratory fitness of children and adolescents representing 19 high-income and upper middle-income countries between 1981 and 2014. Br J Sports Med 53:478-486. doi: 10.1136/bjsports-2017-097982.

18. Tomkinson GR, Kaster T, Dooley FL, Fitzgerald JS, Annandale M, Ferrar K, Lang JJ, Smith JJ (2021) Temporal Trends in the Standing Broad Jump Performance of 10,940,801 Children and Adolescents Between 1960 and 2017. Sports Med 51:531-548. doi: 10.1007/s40279-020-01394-6.

19. Rúa-Alonso M, Rial-Vázquez J, Nine I, Lete-Lasa JR, Clavel I, Giráldez-García MA, Rodríguez-Corral M, Dopico-Calvo X, Iglesias-Soler E (2022) Comparison of Physical Fitness Profiles Obtained before and during COVID-19 Pandemic in Two Independent Large Samples of Children and Adolescents: DAFIS Project. Int J Environ Res Public Health 19:3963. doi: 10.3390/ijerph19073963.

20. Jarnig G, Kerbl R, van Poppel MNM (2022) The Impact of COVID-19-Related Mitigation Measures on the Health and Fitness Status of Primary School Children in Austria: A Longitudinal Study with Data from 708 Children Measured before and during the Ongoing COVID-19 Pandemic. Sports (Basel) 11;10(3):43. doi: 10.3390/sports10030043.

21. Chen S, Wang B, Imagbe S, Gu X, Androzzi J, Liu Y, Yli-Piipari SR, Hu G, Staiano AE (2022) Adolescents Behaviors, Fitness, and Knowledge Related to Active Living before and during the COVID-19 Pandemic: A Repeated Cross-Sectional Analysis. Int J Environ Res Public Health 19:2560. doi: 10.3390/ijerph19052560.
365

22. Zhou T, Zhai X, Wu N, Koriyama S, Wang D, Jin Y, Li W, Sawada SS, Fan X (2022) Changes in Physical Fitness during COVID-19 Pandemic Lockdown among Adolescents: A Longitudinal Study. Healthcare (Basel) 10: 351. doi: 10.3390/healthcare10020351.

366

367

368

369

23. Tsoukos A, Bogdanis GC (2021) The Effects of a Five-Month Lockdown Due to COVID-19 on Physical Fitness Parameters in Adolescent Students: A Comparison between Cohorts. Int J Environ Res Public Health 19:326. doi: 10.3390/ijerph19010326.

370

371

372

373

24. Chambonnière C, Fearnbach N, Pelissier L, Genin P, Fillon A, Boscaro A, Bonjean L, Bailly M, Siroux J, Guirado T, Pereira B, Thivel D, Duclos M (2021). Adverse Collateral Effects of COVID-19 Public Health Restrictions on Physical Fitness and Cognitive Performance in Primary School Children. Int J Environ Res Public Health 18:11099. doi: 10.3390/ijerph182111099

374

375

376

377

378

25. Sunda M, Gilic B, Peric I, Jurcev Savicevic A, Sekulic D (2021). Evidencing the Influence of the COVID-19 Pandemic and Imposed Lockdown Measures on Fitness Status in Adolescents: A Preliminary Report. Healthcare (Basel) 9:681. doi: 10.3390/healthcare9060681.

379

380

381

382

26. Wahl-Alexander Z, Camic CL (2021) Impact of COVID-19 on School-Aged Male and Female Health-Related Fitness Markers. Pediatr Exerc 33:61-64. doi: 10.1123/pes.2020-0208.

383

384

385

27. López-Bueno R, Calatayud J, Andersen LL, Casaña J, Ezzatvar Y, Casajús JA, López-Sánchez GF, Smith L (2021) Cardiorespiratory fitness in adolescents before and after the COVID-19 confinement: a prospective cohort study. Eur J Pediatr 180: 2287-2293. doi: 10.1007/s00431-021-04029-8.

386

387

388

389

28. Deplanque D, Sénéchal-Cohen S, Lemaire F; participants of Giens XXXII, round table n(o) 5 (2017) French Jardé's law and European regulation on drug trials: Harmonization and implementation of new rules. Therapie 72:73-80. doi: 10.1016/j.therap.2016.12.006.

390

391

392

393

29. Cole TJ, Lobstein T (2012). Extended international (IOTF) body mass index cut-offs for thinness, overweight and obesity. Pediatr Obes 7:284-94. doi: 10.1111/j.2047-6310.2012.00064.x.

394
395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

30. Mouraby R, Tafflet M, Nassif H, Toussaint JF, Desgorces FD (2012) Fiabilité et validation de la batterie de tests physiques Diagnoform. Sci sports 27:50-53. doi: 10.1016/j.scispo.2011.01.011

31. Duclos M, Lacomme P, Lambert C, Pereira B, Ren L, Fleury G, Ovigneur H, Deschamps T, Fearnbach N, Vanhelst J, Toussaint JF, Thivel D (2022) Is physical fitness associated with the type of attended school? A cross-sectional analysis among adolescents. J Sports Med Phys Fitness 62: 404-411. doi: 10.23736/S0022-4707.21.12203-0.

32. Vanhelst J, Ternynck C, Ovigneur H, Deschamps T (2019) Normative health-related fitness values for French children: The Diagnoform Programme. Scand J Med Sci Sports 30: 690-699. doi: 10.1111/sms.13607.

33. DeWeese RS, Acciai F, Tulloch D, Lloyd K, Yedidia MJ, Ohri-Vachaspati P (2022) Active commuting to school: A longitudinal analysis examining persistence of behavior over time in four New Jersey cities. Prev Med Rep 26:101718. doi: 10.1016/j.pmedr.2022.101718.

34. Frömel K, Svozil Z, Chmelík F, Jakubec L, Groffik D (2016) The Role of Physical Education Lessons and Recesses in School Lifestyle of Adolescents. J Sch Health 86:143-51. doi: 10.1111/josh.12362.

35. Schmidt SCE, Anedda B, Burchartz A, Eichsteller A, Kolb S, Nigg C, Niessner C, Oriwol D, Worth A, Woll A (2020) Physical activity and screen time of children and adolescents before and during the COVID-19 lockdown in Germany: a natural experiment. Sci Rep 10:21780. doi: 10.1038/s41598-020-78438-4.

36. Gilic B, Zenic N, Separovic V, Jurcev Savicevic A, Sekulic D (2021) Evidencing the influence of pre-pandemic sports participation and substance misuse on physical activity during the COVID-19 lockdown: a prospective analysis among older adolescents. Int J Occup Med Environ Health 34:151-163. doi: 10.13075/ijomeh.1896.01733.
424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

37. López-Bueno R, López-Sánchez GF, Casajús JA, Calatayud J, Gil-Salmerón A, Grabovac I, Tully MA, Smith L (2020) Health-Related Behaviors Among School-Aged Children and Adolescents During the Spanish Covid-19 Confinement. *Front Pediatr* 8:573. doi: 10.3389/fped.2020.00573.

38. Rosselli M, Ermini E, Tosi B, Boddi M, Stefani L, Toncelli L, Modesti PA (2020) Gender differences in barriers to physical activity among adolescents. *Nutr Metab Cardiovasc Dis* 30:1582-1589. doi: 10.1016/j.numecd.2020.05.005.

39. Pietrobelli A, Pecoraro L, Ferruzzi A, Heo M, Faith M, Zoller T, Antoniazzi F, Piacentini G, Fearnbach SN, Heymsfield SB (2020) Effects of COVID-19 Lockdown on Lifestyle Behaviors in Children with Obesity Living in Verona, Italy: A Longitudinal Study. *Obesity (Silver Spring)* 28:1382-1385. doi: 10.1002/oby.22861.

40. Mujika I, Padilla S (2000) Detraining: loss of training-induced physiological and performance adaptations. *Part I: short term insufficient training stimulus. Sports Med* 30:79-87. doi: 10.2165/00007256-200030020-00002.

41. Ma Y, Deng J, Liu Q, Du M, Liu M, Liu J (2022) Long-Term Consequences of COVID-19 at 6 Months and Above: A Systematic Review and Meta-Analysis. *Int J Environ Res Public Health* 19:6865. doi: 10.3390/ijerph19116865.

42. Af Geijerstam A, Mehlig K, Börjesson M, Robertson J, Nyberg J, Adiels M, Rosengren A, Åberg M, Lissner L (2021) Fitness, strength and severity of COVID-19: a prospective register study of 1 559 187 Swedish conscripts. *BMJ Open* 11:e051316. doi: 10.1136/bmjopen-2021-051316.

43. Jeong HC, Lee EJ, Youn HS, So WY (2020) Development and Implementation of a "Music Beeps" Program to Promote Physical Fitness in Adolescents. *Int J Environ Res Public Health* 17:6148. doi: 10.3390/ijerph17176148.
452 44. Lemes VB, Fochesatto CF, Brand C, Gaya ACA, Cristi-Montero C, Gaya AR (2022) Changes in children's self-perceived physical fitness: results from a Physical Education internet-based intervention in COVID-19 school lockdown. Sport Sci Health 30:1-9. doi: 10.1007/s11332-022-00897-1.

455 456 457 45. Yang Y, Koenigstorfer J (2020) Determinants of physical activity maintenance during the Covid-19 pandemic: a focus on fitness apps. Transl Behav Med 10:835-842. doi: 10.1093/tbm/ibaa086.
458 Statements and Declarations

459

460 Conflict of interest

461 The remaining authors state no conflict of interest.

462 Funding

463 There is not support for this research.

464 Authors contributions

465 Jérémy Vanhelst, Laurent Béghin and David Thivel conducted the initial analyses and drafted the initial manuscript.

466

467 Jean-Benoît Baudelet conducted statistical analysis and drafted the initial manuscript.

468 Hervé Ovigneur, Thibault Deschamps designed data collection instruments, coordinated and supervised data collection and reviewed the manuscript.

469

470 All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

471 Ethics approval

472 As this research was not performed to improve biological or medical Human knowledge, this present study is not consider as a clinical research according to French regulatory requirement (“Jardé” law). In this context, this study do not need any approval from an ethical committee.

473

474

475 Consent to participate

476 NA

477 Consent for publication

478 NA
<table><caption>**Table 1.** Characteristics of the study population of adolescents for two cohorts.</caption><thead><tr><th></th><th>Pre lockdown sample</th><th>Post lockdown sample</th><th>P</th></tr></thead><tbody><tr><td><strong>Total</strong></td><td></td><td></td><td></td></tr><tr><td>N</td><td>532</td><td>699</td><td></td></tr><tr><td>Age (y)</td><td>16.5 ± 2.0</td><td>16.6 ± 1.1</td><td>0.17</td></tr><tr><td>Height (cm)</td><td>168.3 ± 8.9</td><td>168.4 ± 10.3</td><td>0.80</td></tr><tr><td>Body mass (kg)</td><td>62.1 ± 12.7</td><td>61.2 ± 12.2</td><td>0.19</td></tr><tr><td>BMI (kg.m<sup>-2</sup>)*</td><td>21.9 ± 3.7</td><td>21.8 ± 7.8</td><td>0.81</td></tr><tr><td><strong>Boys</strong></td><td></td><td></td><td></td></tr><tr><td>N</td><td>318</td><td>325</td><td></td></tr><tr><td>Age (y)</td><td>16.5 ± 2.2</td><td>16.7 ± 1.1</td><td>0.17</td></tr><tr><td>Height (cm)</td><td>172.7 ± 7.6</td><td>174.7 ± 9.2</td><td>0.79</td></tr><tr><td>Body mass (kg)</td><td>65.6 ± 13.4</td><td>65.5 ± 13.2</td><td>0.19</td></tr><tr><td>BMI (kg.m<sup>-2</sup>)*</td><td>21.95 ± 3.98</td><td>21.71 ± 8.25</td><td>0.81</td></tr><tr><td><strong>Girls</strong></td><td></td><td></td><td></td></tr><tr><td>N</td><td>214</td><td>374</td><td></td></tr><tr><td>Age (y)</td><td>16.5 ± 1.6</td><td>16.6 ± 1.1</td><td>0.17</td></tr><tr><td>Height (cm)</td><td>161.8 ± 6.4</td><td>163.0 ± 7.9</td><td>0.80</td></tr><tr><td>Body mass (kg)</td><td>57.0 ± 9.6</td><td>57.4 ± 9.7</td><td>0.19</td></tr><tr><td>BMI (kg.m<sup>-2</sup>)*</td><td>21.76 ± 3.38</td><td>21.86 ± 7.50</td><td>0.81</td></tr></tbody></table>

<footnote>* BMI : Body Mass Index</footnote>
<table><caption>**Table 2.** Physical fitness levels (mean ± SD) according to sex among two cohorts</caption><thead><tr><th></th><th></th><th>Pre lockdown sample</th><th>Post lockdown sample</th><th>P</th></tr></thead><tbody><tr><td rowspan="3">CRF* (m)</td><td>Total</td><td>538.9 ± 101.2</td><td>516.3 ± 159.5</td><td>0.002</td></tr><tr><td>Boys</td><td>575.6 ± 98.0</td><td>579.9 ± 149.9</td><td>0.002</td></tr><tr><td>Girls</td><td>484.4 ± 78.9</td><td>461.0 ± 146.6</td><td>0.002</td></tr><tr><td rowspan="3">LES* (m)</td><td>Total</td><td>184.4 ± 39.4</td><td>161.1 ± 36.3</td><td>&lt; 0.001</td></tr><tr><td>Boys</td><td>203.1 ± 34.1</td><td>184.2 ± 30.9</td><td>&lt; 0.001</td></tr><tr><td>Girls</td><td>156.5 ± 28.9</td><td>141.1 ± 27.7</td><td>&lt; 0.001</td></tr><tr><td rowspan="3">Speed/agility (s)</td><td>Total</td><td>10.8 ± 1.52</td><td>12.1 ± 2.6</td><td>0.003</td></tr><tr><td>Boys</td><td>10.2 ± 1.2</td><td>11.1 ± 2.2</td><td>&lt; 0.001</td></tr><tr><td>Girls</td><td>11.8 ± 1.5</td><td>13.0 ± 2.6</td><td>&lt; 0.001</td></tr><tr><td rowspan="3">UMSE* (n)</td><td>Total</td><td>32.5 ± 21.0</td><td>28.0 ± 19.1</td><td>&lt; 0.001</td></tr><tr><td>Boys</td><td>40.8 ± 20.7</td><td>39.2 ± 19.2</td><td>&lt; 0.001</td></tr><tr><td>Girls</td><td>20.4 ± 14.7</td><td>18.2 ± 12.5</td><td>&lt; 0.001</td></tr><tr><td rowspan="3">LMSE* (cm)</td><td>Total</td><td>931.6 ± 209.2</td><td>835.5 ± 216.1</td><td>&lt; 0.001</td></tr><tr><td>Boys</td><td>1036.3 ± 170.1</td><td>957.1 ± 198.7</td><td>&lt; 0.001</td></tr><tr><td>Girls</td><td>776.1 ± 159.5</td><td>729.8 ± 170.3</td><td>&lt; 0.001</td></tr><tr><td rowspan="3">SBD* (sec)</td><td>Total</td><td>5.0 ± 0.9</td><td>6.5 ± 2.0</td><td>&lt; 0.001</td></tr><tr><td>Boys</td><td>4.7 ± 0.7</td><td>5.3 ± 1.4</td><td>&lt; 0.001</td></tr><tr><td>Girls</td><td>5.6 ± 0.9</td><td>7.0 ± 1.9</td><td>&lt; 0.001</td></tr><tr><td rowspan="3">Coordination (cm)</td><td>Total</td><td>1012.8 ± 167.6</td><td>875.2 ± 195.4</td><td>&lt; 0.001</td></tr><tr><td>Boys</td><td>1096.2 ± 139.8</td><td>989.3 ± 166.9</td><td>&lt; 0.001</td></tr><tr><td>Girls</td><td>888.7 ± 122.9</td><td>776.1 ± 161.5</td><td>&lt; 0.001</td></tr><tr><td rowspan="3">Global score (/20)</td><td>Total</td><td>48.6 ± 16.4</td><td>39.9 ± 17.2</td><td>0.004</td></tr><tr><td>Boys</td><td>57.8 ± 12.6</td><td>52.2 ± 14.5</td><td>0.004</td></tr><tr><td>Girls</td><td>34.9 ± 10.8</td><td>29.1 ± 11.1</td><td>0.004</td></tr></tbody></table>

<footnote>* CRF: Cardiorespiratory fitness; LES: Lower explosive strength; UMSE: Upper muscular strength and endurance; LMSE: Lower muscular strength and endurance; SBD: Speed body displacement.</footnote>
491 **Legends**

492

493 **Figure 1.** Flexibility levels (n) according to sex between pre (T0) and post (T1) lockdown samples.

494

495 **Figure 2.** Difference (%) in physical fitness levels between pre (T0) and post (T1) lockdown samples.
<figure><img src="image_3.png" /></figure>

<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /></figure>

Significant difference were found overall and according to sex (P<0.01).
<figure><img src="image_6.png" /></figure>

All difference were statistically significant (P<0.01).