PHYSICAL INACTIVITY – THE HUMAN HEALTH’S GREATEST ENEMY
Rado PIŠOT1*
1Science and Research Center Koper, Institute for Kinesiology Research, Garibaldijeva ulica1, 6000 Koper, Slovenia 
Received: Nov 30, 2021
Accepted: Dec 2, 2021
Invited editorial
*Corresponding author: Tel. + 386 5 663 77 00; E-mail: rado.pisot@zrs-kp.si
10.2478/sjph-2022-0002 Zdr Varst. 2022;61(1):1-5
1
GIBALNA NEAKTIVNOST – NAJHUJŠI SOVRAŽNIK ČLOVEKOVEGA ZDRAVJA
© National Institute of Public Health, Slovenia. 
Pišot R. Physical inactivity – the human health’s greatest enemy. Zdr Varst. 2022;61(1):1-5. doi: 10.2478/sjph-2022-0002.
ABSTRACT
Keywords: 
contemporary 
society, sedentary 
behaviour, physical 
inactivity, health
IZVLEČEK
Ključne besede: 
sodobna družba, sedeč 
način življenja, gibalna 
neaktivnost, zdravje
For decades, research has been highlighting the positive impact of physical activity on health. Despite the 
immense efforts made by many professional and scientific organizations to raise individual and societal awareness 
about the role of a sufficient quantity and intensity of physical activity in everyday life and to increase the level of 
adherence, the situation is still very worrying. Even more worrying is the fact that increasingly prolonged periods 
of physical inactivity are insidiously and aggressively taking over modern people’s lives – at school, at work, at 
home, even at leisure. It is probably incomprehensible and difficult for many to accept, but physical inactivity is 
becoming the first and worst enemy of health in today’s society.
Raziskave že več destletij izpostavljajo pozitiven vpliv gibalne aktivnosti na zdravje. Kljub neizmernemu 
prizadevanju številnih strokovnih in znanstvenih organizacij v zadnjih desetletjih, da bi posamezniku in družbi 
ozavestili vlogo o pomenu ustrezne količine in intenzivnosti gibalne aktivnosti v vsakdanu človeka ter dvignila 
stopnjo adherence, je stanje še vedno zelo zaskrbljujoče. Še bolj pa nas mora skrbeti dejstvo, da vse daljša 
obdobja gibalne neaktivnosti prikrito in agresivno prevzemajo življenje sodobnega človeka – v šoli, na delovnem 
mestu, v prostem času, doma. Za marsikoga verjetno nerazumljivo in težko sprejemljivo, pa vendar se gibalna 
neaktivnost spreminja v prvega in najhujšega sovražnika zdravja v današnji družbi.
1 INTRODUCTION
Physical activity (PA) is more important for our health 
than ever. It is a lever for physical fitness, working 
efficiency, immune system resilience, and maintenance 
of psychophysical balance. PA is, naturally, central to 
evolution; however, evolution is being undermined by a 
new relationship with gravity, from opposing to acceding. 
Will we survive this devolution?
PA restrictions associated with COVID-19 and high 
exposure to hypokinetic conditions is a phenomenon 
of the sedentary lifestyle we have been witnessing for 
at least the last two decades. In-home lockdowns and 
school and playground closures are only a few restrictions 
imposed by governments. They all greatly affect PA 
patterns. And indeed, a ~50% decrease in moderate and 
vigorous PA (MVPA) with an additional ~50% of increased 
physical inactivity (PI) have been reported  (1, 2), 
leading to the most sedentary period in human history. 
A “sociology of sedentarism”(3) is emerging to study this 
new phenomenon.
The purpose of this paper is to outline the consequences 
of PI studied through more aggressive models (BR case) 
or restriction periods (COVID-19) as well as to explain the 
effects of PA and its dimensions in order to counteract 
these negative effects. 
2 PHYSICAL INACTIVITY – ACUTE EFFECTS OF SHORT 
EXPOSURE TO COMPLETE INACTIVITY  
In young adults PI leads to remodulation of motor units and 
the mechanisms of muscle deterioration, as shown in bed 
rest (BR) studies. The deterioration is very intense after 
just a few days of PI (4, 5). Sudden exercise cessation has 
been associated with rapid onset of insulin resistance (6, 
7) in muscle tissue, decreased muscle glucose utilization, 
and muscle protein degradation with consequent muscle 
atrophy (8). Loss of muscle structure and function (9, 
10)  and increases in insulin resistance accelerate, 
the risk of developing mechanisms which lead to T2D. 
Inactivity-related factors (11) also contribute to reduction 
in cardiorespiratory fitness, bone mineral content, and 
physical function. PI is particularly deleterious in certain 
patient populations, such as those at high risk of T2D (12), 
cardiovascular disease (13), cancer, (14) osteoporosis, 
and mental health (15) and in the elderly, considering 
concomitant sarcopenia or osteoporosis. 
Numerous BR studies demonstrate that the consequences 
of PI on physical and mental health are severe, and the 
mechanisms of deterioration of certain body systems very 
rapid. Circumstances are exacerbated when PI is coupled 
with ageing or comorbidities. PI has a negative impact 
on most subsystems of the human body, among which 
negative consequences were reported on:
10.2478/sjph-2022-0002 Zdr Varst. 2022;61(1):1-5
2
• muscle mass and architecture (9, 16–18);
• muscle function (18, 19);
• bones (20, 21);
• metabolic balance (9, 22)
• cellular oxidative metabolism (23, 24)
• neural processing efficiency (25) and cognitive functions 
(26-28)
• cardiovascular and respiratory functions (29, 30)
The negative effect of hospitalization on patients’ health 
could be partly explained by disease-related problems, 
but also by the sudden reduction in PA. We are challenged 
by the clinically important question regarding overcoming 
the disease and simultaneously preventing secondary 
consequences of disuse (31). Where is the line between 
necessary rest and unnecessary loss? Rest or PI is often 
inappropriately, overly, or unjustifiably prescribed for 
certain injuries and illnesses.
3 PHYSICAL INACTIVITY FOR LONG PERIODS AND THE 
COVID-19 EXPERIENCE
As more governments tighten quarantine or consider 
various forms of lock-down to prevent the spread of 
COVID-19 (32), a major concern arises regarding the 
potential negative impact of PI due to personal limitations 
(13). The consequences of COVID-19 restrictions are like 
those at post-complete PI. Subjects included in the BR 
study after 2 months of lockdown show a comparable 
increase in insulin resistance. Lockdown led to about a 
75% decrease in daily step count, with concomitant ill 
effects (e.g. weight gain).
We have conducted several studies during COVID-19 
restrictions. Although even before the pandemic, most 
adults failed to meet the minimum daily recommendations, 
we noted an additional 40% decrease of MVPA, a 40% 
decrease in walking time, and a 30% increase of PI (33). 
Focusing on the prevalent PI, we soon discovered that the 
highest increase occurred in the amount of sitting time, 
and within that of screen time (by as much as 60%), which 
was related to weight gain (2). Before the pandemic as 
many as 80% of children were involved in organized sports 
activities; now around 90% of children do not/cannot 
engage in them. The SLO fit study (34) revealed a striking 
deterioration of motor skills and physical characteristics 
of children in Slovenia, recording the lowest levels in the 
history of such monitoring.
Consistently meeting PA guidelines was strongly associated 
with a reduced risk for severe COVID-19 outcomes among 
infected adults. Patients with COVID-19 who were 
consistently inactive had a greater risk of hospitalization, 
admission to the ICU or death than patients who 
consistently met PA guidelines (35).  
10.2478/sjph-2022-0002 Zdr Varst. 2022;61(1):1-5
3
4 RELATIONSHIP BETWEEN PHYSICAL ACTIVITY, 
PHYSICAL INACTIVITY, AND HEALTH
Over three decades ago, the WHO issued recommendations 
for sufficient exercise, noting the correlation between 
regular physical exercise and health. Given that the 
most recent global estimates (36) show that one in four 
(27.5%) adults and more than three-quarters (81%) (37) of 
adolescents fail to meet the recommendations for aerobic 
exercise, there is an urgent need to increase PA.  
Exercise is, in terms of amount and intensity, correlated 
with health risk factors according to the U-shaped curve 
model (Figure 1).
Lack of PA (A) is a very strong health risk factor. Moderate-
to-vigorous PA (MVPA) represents the ideal ratio and 
stimulates the mechanisms for preserving metabolic and 
cardiovascular health, while very vigorous PA can even be 
harmful, particularly due to strain and musculoskeletal 
injuries. 
The worst threat to health remains PI, which shows 
little interdependence with MVPA. We are witnessing 
increasingly long periods of PI in both active and inactive 
populations. A recent study (38) of young college athletes 
and their inactive peers highlighted a very interesting 
phenomenon, finding that there is no difference in mean 
sitting time (10.96±2.98 hours) between athletes and 
non-athletes. Because of the independent relationship 
between MVPA time and sitting time, athletes can be 
highly active and highly sedentary at the same time, so 
that there is a harmful net effect on their health. The 
meta-analysis (39) conducted to estimate the pooled 
mean of time spent in PA and sedentary time concluded 
that interventions delivered during childcare and school 
might produce better results if they focus on reducing PI/
sedentary time, rather than promoting PA.
Studies indicate that safe and responsible health-related 
behaviour is that which makes sure we are sufficiently 
physically active every day and sedentary as little as 
possible (Figure 2): between 40 and 60 min of MVPA daily, 
when we are not physically inactive (sedentary) for more 
than 4 hours in total and these periods of inactivity do not 
last more than 40 minutes at a time. 
Figure 1. 
Legend: A – 0 to LPA (low PA); B – MPA (moderate PA);  
C – MVPA (moderate-to-vigorous); D – VPA – OVERUSE/INJURY 
(vigorous-to-overuse)
Correlation between amount and intensity of exercise 
and health hazard.
Figure 2. Schematic representation of physical inactivity and MVPA effecting our health.
Legend: Physical inactivity min/
day; MVPA – moderate-to-vigorous 
physical activity min/day
5 CONCLUSION
Sedentary behaviour is associated with the early onset 
of noncommunicable chronic diseases that lead to health 
problems and to all-cause mortality, regardless of other 
risk factors. Although PI progresses to the second risk 
factor of overall mortality – in 2006 it was the 7th (40) – it 
should be noted that it is the most easily modifiable health 
factor in all age groups. As a “silent killer”, its effects may 
go undetected for years or decades before a preventable 
disease develops from it.
Many scientific publications consider PI a pandemic, 
supporting the publication of the WHO Global Plan of Action 
for Physical Activity 2018–2030 (37). This document aims to 
provoke a relative reduction in PI of 10% by 2025 and of 15% 
by 2030, which will contribute to longer life expectancy 
and a higher quality of life. Ensuring sufficient, high-quality 
PA must be addressed separately from reducing PI in the 
most vulnerable subgroups. PA and PI are two separate 
and weakly correlated phenotypes, they may include the 
same or completely different groups of individuals, with 
the need for various interventions and tools. 
The goal is to achieve less than 4 sitting hours a day, in 
shorter periods, and at least 1 hour of MVPA. Do we need 
restrictions to limit sedentary behaviour? Do we need to 
introduce taxes on unnecessary sitting hours for inactive 
healthy people, on the use of elevators, limit time in front 
of screens, etc.? It would probably be easier than waiting for 
general awareness of the positive effects of PA to emerge.
CONFLICTS OF INTEREST 
The author declares no conflicts of interest.
FUNDING 
This editorial was carried out without external funding.
ETHICAL APPROVAL 
Ethical approval for this editorial is not needed.
REFERENCES
1. Ammar A, Brach M, Trabelsi K, Chtourou H, Boukhris O, Masmoudi 
L, et al. Effects of COVID-19 home confinement on eating behaviour 
and physical activity: results of the ECLB-COVID19 international online 
survey. Nutrients. 2020;12(6):1583. doi: 10.3390/nu12061583.
2. Pišot S, Milovanović I, Šimunič B, Gentile A, Bosnar K, Prot F, et al. 
Maintaining everyday life praxis in the time of COVID-19 pandemic 
measures (ELP-COVID-19 survey). Eur J Public Health. 2020;30(6):1181–
6. doi: 10.1093/eurpub/ckaa157.
3. Pišot S, Pišot R. Decline in motor competences in contemporary 
society : time for a sociology of sedentarism? Assur Act Environ 
Healthy Child Adolesc Book Abstr. Accessed  Oct 7, 2019 at: https://
www.zrs-kp.si/wp-content/uploads/2019/11/OVG_ZBORNIK_2019_
spletna_izdaja.pdf.
4. Monti E, Reggiani C, Franchi MV, Toniolo L, Sandri M, Armani A, et al. 
Neuromuscular junction instability and altered intracellular calcium 
handling as early determinants of force loss during unloading in 
humans. J Physiol. 2021;599(12):3037–61. doi: 10.1113/JP281365.
5. Sarto F, Monti E, Šimunič B, Pišot R, Narici MV, Franchi MV. Changes 
in biceps femoris long head fascicle length after 10-d bed rest 
assessed with different ultrasound methods. Med Sci Sports Exerc. 
2021;53(7):1529–36. doi: 10.1249/MSS.0000000000002614.
6. Mazzucco S, Agostini F, Biolo G. Inactivity-mediated insulin resistance 
is associated with upregulated pro-inflammatory fatty acids in 
human cell membranes. Clin Nutr. 2010;29(3):386–90. doi: 10.1016/j.
clnu.2009.09.006.
7. Reidy PT, Monnig JM, Pickering CE, Funai K, Drummond MJ. Preclinical 
rodent models of physical inactivity-induced muscle insulin resistance: 
challenges and solutions. J Appl Physiol. 2021;130(3):537–44. doi: 
10.1152/japplphysiol.00954.2020.
8. Charansonney OL. Physical activity and aging: a life-long story. Discov 
Med. 2011;12(64):177–85. 
9. Pišot R, Marusic U, Biolo G, Mazzucco S, Lazzer S, Grassi B, et al. 
Greater loss in muscle mass and function but smaller metabolic 
alterations in older compared with younger men following 2 wk of 
bed rest and recovery. J Appl Physiol. 2016;120(8):922–9. doi: 10.1152/
japplphysiol.00858.2015.
10. Pratt J, De Vito G, Narici M, Boreham C. Neuromuscular junction 
aging: a role for biomarkers and exercise. J Gerontol A Biol Sci Med 
Sci. 2021;76(4):576–85. 
11. Bowden Davies KA, Pickles S, Sprung VS, Kemp GJ, Alam U, Moore DR, 
et al. Reduced physical activity in young and older adults: metabolic 
and musculoskeletal implications. Ther Adv Endocrinol Metab. 
2019;10:2042018819888824. 
12. Bhaskarabhatla KV, Birrer R. Physical activity and diabetes mellitus. 
Compr Ther. 2005;31(4):291–8. 
13. Lippi G, Henry BM, Sanchis-Gomar F. Physical inactivity and 
cardiovascular disease at the time of coronavirus disease 
2019 (COVID-19). Eur J Prev Cardiol. 2020;27(9):906–8. doi: 
10.1177/2047487320916823.
14. Sanchis-Gomar F, Lucia A, Yvert T, Ruiz-Casado A, Pareja-Galeano H, 
Santos-Lozano A, et al. Physical inactivity and low fitness deserve 
more attention to alter cancer risk and prognosis. Cancer Prev Res 
Phila Pa. 2015;8(2):105–10. doi: 10.1158/1940-6207.CAPR-14-0320.
15. Brooks SK, Webster RK, Smith LE, Woodland L, Wessely S, Greenberg 
N, et al. The psychological impact of quarantine and how to reduce 
it: rapid review of the evidence. The Lancet. 2020;395(10227):912–20. 
doi: 10.1016/S0140-6736(20)30460-8.
16. de Boer MD, Seynnes OR, di Prampero PE, Pišot R, Mekjavić IB, Biolo G, 
et al. Effect of 5 weeks horizontal bed rest on human muscle thickness 
and architecture of weight bearing and non-weight bearing muscles. 
Eur J Appl Physiol. 2008;104(2):401–7. doi: 10.1007/s00421-008-0703-0.
4
10.2478/sjph-2022-0002 Zdr Varst. 2022;61(1):1-5
17. Šimunič B, Koren K, Rittweger J, Lazzer S, Reggiani C, Rejc E, et al. 
Tensiomyography detects early hallmarks of bed-rest-induced atrophy 
before changes in muscle architecture. J Appl Physiol. 2019;126(4):815–
22. doi: 10.1152/japplphysiol.00880.2018.
18. Marusic U, Narici M, Simunic B, Pisot R, Ritzmann R. Nonuniform loss 
of muscle strength and atrophy during bed rest: a systematic review. 
J Appl Physiol Bethesda Md 1985. 2021;131(1):194–206. 
19. Rejc E, di Prampero PE, Lazzer S, Grassi B, Simunic B, Pisot R, et al. 
Maximal explosive power of the lower limbs before and after 35 days 
of bed rest under different diet energy intake. Eur J Appl Physiol. 
2015;115(2):429–36. doi: 10.1007/s00421-014-3024-5.
20. Rittweger J, Simunic B, Bilancio G, Gaspare De Santo N, Cirillo M, 
Biolo G, et al. Bone loss in the lower leg during 35 days of bed rest is 
predominantly from the cortical compartment. Bone. 2009;44(4):612–
8. doi: 10.1016/j.bone.2009.01.001.
21. Konda NN, Karri RS, Winnard A, Nasser M, Evetts S, Boudreau E, et 
al. A comparison of exercise interventions from bed rest studies for 
the prevention of musculoskeletal loss. Npj Microgravity. 2019;5(1):12. 
doi: 10.1038/s41526-019-0073-4.
22. Biolo G, Agostini F, Simunic B, Sturma M, Torelli L, Preiser JC, et al. 
Positive energy balance is associated with accelerated muscle atrophy 
and increased erythrocyte glutathione turnover during 5 wk of bed 
rest. Am J Clin Nutr. 2008;88(4):950–8. doi: 10.1093/ajcn/88.4.950.
23. Porcelli S, Marzorati M, Lanfranconi F, Vago P, Pišot R, Grassi B. Role 
of skeletal muscles impairment and brain oxygenation in limiting 
oxidative metabolism during exercise after bed rest. J Appl Physiol. 
2010;109(1):101–11. doi: 10.1152/japplphysiol.00782.2009.
24. Salvadego D, Lazzer S, Marzorati M, Porcelli S, Rejc E, Šimunič B, et 
al. Functional impairment of skeletal muscle oxidative metabolism 
during knee extension exercise after bed rest. J Appl Physiol. 
2011;111(6):1719–26. doi: 10.1152/japplphysiol.01380.2010.
25. Marušič U, Pišot R, Kavčič V. Higher neural demands on stimulus 
processing after prolonged hospitalization can be mitigated by a 
cognitively stimulating environment. Psihol Obz Horiz Psychol. 
2021;55–61. doi: 10.20419/2021.30.536.
26. Alosco ML, Spitznagel MB, Cohen R, Raz N, Sweet LH, Josephson R, 
et al. Decreased physical activity predicts cognitive dysfunction and 
reduced cerebral blood flow in heart failure. J Neurol Sci. 2014;339(1–
2):169–75. 
27. Marusic U, Grosprêtre S. Non-physical approaches to counteract age-
related functional deterioration: applications for rehabilitation and 
neural mechanisms. Eur J Sport Sci. 2018;18(5):639–49. 
28. Tement M, Selič - Zupančič P. Quality of life and health status in 
middle-aged presumed healthy Slovenian family practice attendees. 
Zdr Varst. 2021;60(3):182-189. doi: 10.2478/sjph-2021-0026.
29. Petek D, Petek-Ster M, Tusek-Bunc K. Health behavior and health-
related quality of life in patients with a high risk of cardiovascular 
disease. Zdr Varst. 2018;57(1):39–46. doi: /10.2478/sjph-2018-0006.
30. Thijssen DHJ, Green DJ, Hopman MTE. Blood vessel remodeling and 
physical inactivity in humans. J Appl Physiol. 2011;111(6):1836–45. doi: 
10.1152/japplphysiol.00394.2011.
31. Veninšek G, Gabrovec B. Management of frailty at individual level 
– clinical management: systematic literature review. Zdr Varst. 
2018;57(2):106–15. doi: 10.2478/sjph-2018-0014.
32. The Lancet. COVID-19: too little, too late? Lancet. 2020;395(10226):755. 
doi:  10.1016/S0140-6736(20)30522-5.
33. Ammar A, Chtourou H, Boukhris O, Trabelsi K, Masmoudi L, Brach 
M, et al. COVID-19 home confinement negatively impacts social 
participation and life satisfaction: a worldwide multicenter study. Int 
J Environ Res Public Health. 2020;17(17):E6237. 
34. Starc G, Strel J, Kovač M, Leskovšek B, Sorić M, Jurak G. SLOfit 2020: 
poročilo o telesnem in gibalnem razvoju otrok in mladine v šolskem 
letu 2019/20. Ljubljana: Fakulteta za šport, Inštitut za kineziologijo, 
2020. 
35. Sallis R, Young DR, Tartof SY, Sallis JF, Sall J, Li Q, et al. Physical 
inactivity is associated with a higher risk for severe COVID-19 outcomes: 
a study in 48 440 adult patients. Br J Sports Med. 2021;55(19):1099–
105. doi: 10.1136/bjsports-2021-104080.
36. Bull FC, Al-Ansari SS, Biddle S, Borodulin K, Buman MP, Cardon G, et 
al. World Health Organization 2020 guidelines on physical activity 
and sedentary behaviour. Br J Sports Med. 2020;54(24):1451–62. doi: 
10.1136/bjsports-2020-102955.
37. Guthold R, Stevens GA, Riley LM, Bull FC. Worldwide trends in 
insufficient physical activity from 2001 to 2016: a pooled analysis of 
358 population-based surveys with 1·9 million participants. Lancet 
Glob Health. 2018;6(10):e1077–86. doi: 10.1016/S2214-109X(18)30357-7.
38. Academy USS. Sitting time and physical activity comparison between 
student athletes and non-athletes: a pilot study. Sport J. 2020. 
Accessed Nov 30, 2021 at: https://thesportjournal.org/article/sitting-
time-and-physical-activity-comparison-between-student-athletes-
and-non-athletes-a-pilot-study/.
39. Tassitano RM, Weaver RG, Tenório MCM, Brazendale K, Beets MW. 
Physical activity and sedentary time of youth in structured settings: 
a systematic review and meta-analysis. Int J Behav Nutr Phys Act. 
2020;17(1):160. doi: 10.1186/s12966-020-01054-y.
40. Kessler M, Thumé E, Scholes S, Marmot M, Facchini LA, Nunes BP, et 
al. Modifiable risk factors for 9-year mortality in older English and 
Brazilian adults: the ELSA and SIGa-Bagé ageing cohorts. Sci Rep. 
2020;10(1):4375. doi: 10.1038/s41598-020-61127-7.
5
10.2478/sjph-2022-0002 Zdr Varst. 2022;61(1):1-5