Can Cognitive Activities during Breaks in Repetitive Manual Work Accelerate Recovery from Fatigue? A Controlled Experiment

Neurophysiologic theory and some empirical evidence suggest that fatigue caused by physical work may be more effectively recovered during “diverting” periods of cognitive activity than during passive rest; a phenomenon of great interest in working life. We investigated the extent to which development and recovery of fatigue during repeated bouts of an occupationally relevant reaching task was influenced by the difficulty of a cognitive activity between these bouts. Eighteen male volunteers performed three experimental sessions, consisting of six 7-min bouts of reaching alternating with 3 minutes of a memory test differing in difficulty between sessions. Throughout each session, recordings were made of upper trapezius muscle activity using electromyography (EMG), heart rate and heart rate variability (HRV) using electrocardiography, arterial blood pressure, and perceived fatigue (Borg CR10 scale and SOFI). A test battery before, immediately after and 1 hour after the work period included measurements of maximal shoulder elevation strength (MVC), pressure pain threshold (PPT) over the trapezius muscles, and a submaximal isometric contraction. As expected, perceived fatigue and EMG amplitude increased during the physical work bouts. Recovery did occur between the bouts, but fatigue accumulated throughout the work period. Neither EMG changes nor recovery of perceived fatigue during breaks were influenced by cognitive task difficulty, while heart rate and HRV recovered the most during breaks with the most difficult task. Recovery of perceived fatigue after the 1 hour work period was also most pronounced for the most difficult cognitive condition, while MVC and PPT showed ambiguous patterns, and EMG recovered similarly after all three cognitive protocols. Thus, we could confirm that cognitive tasks between bouts of fatiguing physical work can, indeed, accelerate recovery of some factors associated with fatigue, even if benefits may be moderate and some responses may be equivocal. Our results encourage further research into combinations of physical and mental tasks in an occupational context.

[1]  G. Hagg,et al.  Static work loads and occupational myalgia a new explanation model , 1991 .

[2]  J Winkel,et al.  Ergonomic effects of a management-based rationalization in assembly work - a case study. , 1996, Applied ergonomics.

[3]  W. Rohmert.  Ermittlung von Erholungspausen für statische Arbeit des Menschen , 1960, Internationale Zeitschrift für angewandte Physiologie einschließlich Arbeitsphysiologie.

[4]  J Eklund,et al.  Improving meat cutters' work: changes and effects following an intervention. , 2013, Applied ergonomics.

[5]  L Finsen,et al.  Acute response to precision, time pressure and mental demand during simulated computer work. , 2000, Scandinavian journal of work, environment & health.

[6]  Inge Zijdewind,et al.  Interaction between force production and cognitive performance in humans , 2006, Clinical Neurophysiology.

[7]  S. Gandevia,et al.  Projection of low-threshold afferents from human intercostal muscles to the cerebral cortex. , 1989, Respiration physiology.

[8]  R. Enoka.  Muscle fatigue--from motor units to clinical symptoms. , 2012, Journal of biomechanics.

[9]  D B Chaffin,et al.  Shoulder disorders and postural stress in automobile assembly work. , 2000, Scandinavian journal of work, environment & health.

[10]  Grace P. Y. Szeto,et al.  Effects of physical and mental task demands on cervical and upper limb muscle activity and physiological responses during computer tasks and recovery periods , 2011, European Journal of Applied Physiology.

[11]  Svend Erik Mathiassen.  The influence of exercise/rest schedule on the physiological and psychophysical response to isometric shoulder-neck exercise , 2004, European Journal of Applied Physiology and Occupational Physiology.

[12]  R E Janaro,et al.  A Study of the Reduction of Fatigue Impact on Productivity through Optimal Rest Break Scheduling , 1985, Human factors.

[13]  Karen Søgaard,et al.  The importance of the work/rest pattern as a risk factor in repetitive monotonous work. , 2000 .

[14]  S E Mathiassen,et al.  Physiological comparison of three interventions in light assembly work: reduced work pace, increased break allowance and shortened working days , 1996, International archives of occupational and environmental health.

[15]  S. Konz.  Work/rest: Part II – The scientific basis (knowledge base) for the guide1 , 2000 .

[16]  V. Napadow,et al.  The Autonomic Brain: An Activation Likelihood Estimation Meta-Analysis for Central Processing of Autonomic Function , 2013, The Journal of Neuroscience.

[17]  F. Togo,et al.  Heart rate variability in occupational health --a systematic review. , 2009, Industrial health.

[18]  A. Crenshaw,et al.  Changes in interstitial noradrenaline, trapezius muscle activity and oxygen saturation during low-load work and recovery , 2009, European Journal of Applied Physiology.

[19]  G M Hägg,et al.  Methodologies for evaluating electromyographic field data in ergonomics. , 2000, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[20]  T. Beck,et al.  The Effects of Diverting Activities on Recovery from Fatiguing Concentric Isokinetic Muscle Actions , 2011, Journal of strength and conditioning research.

[21]  G. Mirka,et al.  Cervicobrachial muscle response to cognitive load in a dual-task scenario , 2004, Ergonomics.

[22]  G M Hägg,et al.  Normalization of surface EMG amplitude from the upper trapezius muscle in ergonomic studies - A review. , 1995, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[23]  Michiel P de Looze,et al.  Effects of software programs stimulating regular breaks and exercises on work-related neck and upper-limb disorders. , 2003, Scandinavian journal of work, environment & health.

[24]  S. Mathiassen,et al.  Motor variability in occupational health and performance. , 2012, Clinical biomechanics.

[25]  P. Hassmén,et al.  Psychophysiological stress and emg activity of the trapezius muscle , 1994, International journal of behavioral medicine.

[26]  Michael F. Bunting,et al.  How does running memory span work? , 2006, Quarterly journal of experimental psychology.

[27]  H. Johansson,et al.  Position sense acuity is diminished following repetitive low-intensity work to fatigue in a simulated occupational setting , 2000, European Journal of Applied Physiology.

[28]  M. Malik.  Heart Rate Variability , 1996, Clinical cardiology.

[29]  E P Takala,et al.  Effects of changes in work methods on musculoskeletal load. An intervention study in the trailer assembly. , 1997, Applied ergonomics.

[30]  A D Price,et al.  Calculating relaxation allowances for construction operatives - part 2: local muscle fatigue. , 1990, Applied ergonomics.

[31]  Ranjana K. Mehta,et al.  Effects of concurrent physical and mental demands for a short duration static task , 2011 .

[32]  T. Waters,et al.  The Impact of Mental Processing and Pacing on Spine Loading: 2002 Volvo Award in Biomechanics , 2002, Spine.

[33]  Peter J Keir,et al.  Interfering effects of multitasking on muscle activity in the upper extremity. , 2007, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[34]  Tejin Yoon,et al.  Sex differences in response to cognitive stress during a fatiguing contraction. , 2009, Journal of applied physiology.

[35]  M Christmansson,et al.  Task design, psycho-social work climate and upper extremity pain disorders--effects of an organisational redesign on manual repetitive assembly jobs. , 1999, Applied ergonomics.

[36]  Keith T Palmer,et al.  Work relatedness of chronic neck pain with physical findings--a systematic review. , 2007, Scandinavian journal of work, environment & health.

[37]  S. Bechtold,et al.  Maximization of Labor Productivity Through Optimal Rest-Break Schedules , 1984 .

[38]  Richard P Wells,et al.  The effects of job rotation on the risk of reporting low back pain , 2003, Ergonomics.

[39]  Dario Farina,et al.  Standardising surface electromyogram recordings for assessment of activity and fatigue in the human upper trapezius muscle , 2002, European Journal of Applied Physiology.

[40]  J H van Dieën,et al.  Temporal strategy and performance during a fatiguing short-cycle repetitive task , 2012, Ergonomics.

[41]  Karen Søgaard,et al.  The effect of physical and psychosocial loads on the trapezius muscle activity during computer keying tasks and rest periods , 2004, European Journal of Applied Physiology.

[42]  Tim Bosch,et al.  The influence of task variation on manifestation of fatigue is ambiguous – a literature review , 2014, Ergonomics.

[43]  R A Henning,et al.  Frequent short rest breaks from computer work: effects on productivity and well-being at two field sites. , 1997, Ergonomics.

[44]  Kerstina Ohlsson,et al.  Rationalization in meat cutting - consequences on physical workload. , 2012, Applied ergonomics.

[45]  E. Heath.  Borg's Perceived Exertion and Pain Scales , 1998 .

[46]  Kermit Davis,et al.  Ergonomics. Pros and cons of job rotation as a means of reducing injury costs. , 2005, Journal of occupational and environmental hygiene.

[47]  Scott Haldeman,et al.  The Burden and Determinants of Neck Pain in Workers: Results of the Bone and Joint Decade 2000–2010 Task Force on Neck Pain and Its Associated Disorders , 2008, Spine.

[48]  A. Dababneh,et al.  Impact of added rest breaks on the productivity and well being of workers , 2001, Ergonomics.

[49]  M. Hagberg,et al.  The effects of different pause types on neck and shoulder EMG activity during VDU work. , 1989, Ergonomics.

[50]  Maury A. Nussbaum,et al.  Ergonomic evaluation of hospital bed design features during patient handling tasks , 2011 .

[51]  Jose Antonio Diego-Mas,et al.  A multi-criteria genetic algorithm for the generation of job rotation schedules. , 2009 .

[52]  Ranjana K. Mehta,et al.  Influence of mental workload on muscle endurance, fatigue, and recovery during intermittent static work , 2011, European Journal of Applied Physiology.

[53]  L Finsen,et al.  Influence of memory demand and contra lateral activity on muscle activity. , 2001, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[54]  A. Malliani,et al.  Heart rate variability. Standards of measurement, physiological interpretation, and clinical use , 1996 .

[55]  Ramaratnam R Bishu,et al.  Review and evaluation of techniques for determining fatigue allowances , 1991 .

[56]  E. Asmussen,et al.  Recuperation after muscular fatigue by “diverting activities” , 1978, European Journal of Applied Physiology and Occupational Physiology.

[57]  Timothy D. Lee,et al.  Motor Control and Learning: A Behavioral Emphasis , 1982 .

[58]  E. Asmussen,et al.  A central nervous component in local muscular fatigue , 1978, European Journal of Applied Physiology and Occupational Physiology.

[59]  G. Sjøgaard.  Potassium and fatigue: the pros and cons. , 1996, Acta physiologica Scandinavica.

[60]  Svend Erik Mathiassen,et al.  Time--a key issue for musculoskeletal health and manufacturing. , 2007, Applied ergonomics.

[61]  Bart Visser,et al.  Pathophysiology of upper extremity muscle disorders. , 2006, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[62]  J. Thayer,et al.  eview meta-analysis of heart rate variability and neuroimaging studies : Implications or heart rate variability as a marker of stress and health , 2012 .

[63]  H. Monod,et al.  Capacité de travail statique d'un groupe musculaire synergique chez l'homme. , 1957 .

[64]  Svend Erik Mathiassen,et al.  Diversity and variation in biomechanical exposure: what is it, and why would we like to know? , 2006, Applied ergonomics.

[65]  Leanna M. Horton,et al.  Effects of rotation frequency and task order on localised muscle fatigue and performance during repetitive static shoulder exertions , 2012, Ergonomics.

[66]  M. Frings-Dresen,et al.  Effect of job rotation on need for recovery, musculoskeletal complaints, and sick leave due to musculoskeletal complaints: a prospective study among refuse collectors. , 2005, American journal of industrial medicine.

[67]  E. Åhsberg.  Dimensions of fatigue in different working populations. , 2000, Scandinavian journal of psychology.

[68]  Ranjana K Mehta,et al.  Muscle- and task-dependent responses to concurrent physical and mental workload during intermittent static work , 2012, Ergonomics.

[69]  M S Redfern,et al.  Designing safe job rotation schedules using optimization and heuristic search , 2000, Ergonomics.

[70]  Svend Erik Mathiassen,et al.  Changes in physical workload with implementation of mouse-based information technology in air traffic control , 2006 .

[71]  G M Hägg,et al.  Normalization of upper trapezius EMG amplitude in ergonomic studies. , 1995, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[72]  Scott Haldeman,et al.  The burden and determinants of neck pain in workers: results of the Bone and Joint Decade 2000-2010 Task Force on Neck Pain and Its Associated Disorders. , 2009, Journal of manipulative and physiological therapeutics.

[73]  A. Silman,et al.  Occupational risk factors for shoulder pain: a systematic review , 2000, Occupational and environmental medicine.

[74]  S. Gandevia.  Spinal and supraspinal factors in human muscle fatigue. , 2001, Physiological reviews.

[75]  A J Spaepen,et al.  Muscular activity of the shoulder and neck region during sustained and intermittent exercise. , 1997, Clinical physiology.

[76]  Dario Farina,et al.  Periodic increases in force during sustained contraction reduce fatigue and facilitate spatial redistribution of trapezius muscle activity , 2007, Experimental Brain Research.

[77]  Peter J Keir,et al.  Task rotation effects on upper extremity and back muscle activity. , 2011, Applied ergonomics.

[78]  P. Tomporowski.  Effects of acute bouts of exercise on cognition. , 2003, Acta psychologica.

[79]  A M Genaidy,et al.  Active microbreak effects on musculoskeletal comfort ratings in meatpacking plants. , 1995, Ergonomics.

[80]  J. Graydon,et al.  The time course effect of moderate intensity exercise on response execution and response inhibition , 2009, Brain and Cognition.

[81]  Alex Burdorf,et al.  Associations between work-related factors and specific disorders of the shoulder--a systematic review of the literature. , 2010, Scandinavian journal of work, environment & health.