MEDICAL CHALLENGES: EFFECTS of TRAVEL FATIGUE and JET LAG Prof Christa Janse van Rensburg MBChB, MSc, MMed, MD FACSM, FFIMS Sports Medicine & SEMLI, University of Pretoria Consultant Rheumatologist, Eugene Marais Hospital South Africa IOC Advanced Team Physician Course TOKYO, 01-03 JULY 2019 INTRODUCTION @ChristaJVR #IOCATPC2019 No disclosures A) CIRCADIAN SYSTEM ~24h self-sustained variation in physical, mental & behavioural function • Functions endogenously: ✓autonomous ✓rhythm maintained in absence of external cues • Circadian timing: Master Clock: Suprachiasmatic nucleus (SCN) in HT Peripheral Clocks: in mostly every cell of all tissue REGULATION • Complex series of interlocking transcriptional feedback loops (clock genes that code for clock proteins) • Various stimuli = zeitgebers or "time givers” ✓ Light/dark cycle most NB advance or delay phase • Rhythmical change phase response curve (PRC) - Amount of phase shift depends on zeitgeber: - timing - intensity - duration - frequency - Synergistic or antagonistic action of zeitgebers i.e. interact in ‘push’ or ‘pull’ on circadian rhythm phase • Inter-individual variations - Chronotype differences (morning lark vs. night owl) The Nobel Prize in Physiology or Medicine 2017 - Genetic variances of circadian-related phenotypes was awarded jointly to Rosbash M, Young MW, Hall JC for their pioneering discovery that our [Period (PER1, PER2, PER3); Cryptochrome (CRY1,CRY2) circadian clocks are regulated by a small group genes] of genes working at individual cell level. CIRCADIAN RHYTHM DESYNCHRONISATION • Explained in one of 3 ways: ✓Temporary misalignment between external environment (@ destination time-zone) & timing of internal CR ✓Dysfunction of the circadian clock e.g. due to polymorphisms in human clock genes (PER3) ✓Dysfunction of the efferent and/or afferent pathways • Jet lag internal circadian system cannot keep up with rapid light/dark change adaptation to new environment • Entrainment of CR - Inputs from retina, melatonin receptors, brain (CNS arousal) - reset by exposure to external stimuli - bright light/darkness, melatonin, exercise, meal times, etc. B) TRAVEL ISSUES Travel Fatigue Jet Lag Motion sickness DVT Other TRAVEL FATIGUE & JET LAG Uncontrollable factors Controllable factors • Passenger next to you • Journey anxiety • Confined space • Nutrition • Length of flight • Hydration • Crossing time zones (extra 15-20ml for each hour in • flight) Altitude changes (poor air quality) • Time of sleep • Air pressure fluctuations • Body temperature • Stopovers /Delays • Movement / activity • Turbulence • Vibration /Noise Travel fatigue Jet lag Definition Temporary exhaustion, tiredness TemporaryBody`s daily disorder rhythms / outdesynchronosis of sync with * destination time zone Mechanism / Associated with any long journey Rapid long-distance, trans-meridian Cause (irrespective of mode of transport) travel Flight’s direction > length Direction of N S W E travel Seasonal change Shift in local time e.g. Depart from JHB at 30°C, disembark in e.g. Depart 10h00 from London, arrive 13h00 Frankfurt at 0°C in NY (watch indicating London time 18h00) W E = 8-hour flight across 5 time zones 2 time zones in any direction 3 time zones in directions E-W / W-E Travel fatigue Jet lag Duration • Subsides next day / after shower / • Lasts several days to weeks night’s sleep • Resolves with resynchronisation • Quicker overcome BUT can • 1 day/time zone accumulate over course of season • Can be persistent & impact athlete’s capacity to recover & perform Severity • Vast inter- & intra-individual variations • Frequency of trips & length of season play a role Travel Direction and Body Clock Eastward Westward Phase shift • Advance (!!only if <8 hrs time zone • Delay (up to 12 hrs time zone difference) BodyNB! clock cycle difference, otherwise same as westward) Travel: • Shorten 60 min/d (each day in new time • Extend 90 min/d (each day in new time • Direction zone) longer to adapt zone) shorter to adapt • Distance • Frequency • More difficult (easier for morning type • Easier for most travellers Season length person) Sleep pattern • Difficult to fall asleep • Sleepy early evening • Difficult to wake up • Wake up early C) POTENTIAL IMPLICATIONS Hypoxia Circadian rhythm disruption Improved performance (2-11%): ✓Neuromuscular function ✓VO2max ✓Grip strength ✓Peak force of big muscle groups Fatigue Mood Disrupted sleep Illness Injury D) HOW TO COPE? Management of: • Environmental challenges • Travel fatigue & Jet lag • Much effort, mainly to shift CR only partial success • Effects depend on internal circadian time of treatment Circadian phase determined by: ✓ Melatonin (plasma, salivary or urinary) ✓ Habitual sleep onset at home ✓ CBTmin Diet: Bright light: EAST - late evening delays - timing of meal xBiological night time - morning (after CBTmin) seems more NB WEST dvancesadvances than type of meal Low dose melatonin: Sleep: - very late evening to - pre-adapt by morning delays shifting schedule - mid-afternoon to bed-time towards time at advances destination - power naps Exercise: - avoid sleep debt - cannot reliably shift CR - may maintain arousal level - early morning exercise may delay - early evening exercise may advance Sunrise: TRAVEL SCENARIO 04:47am Sunset: South African Olympic Team travelling to the 18:47pm 2020 Summer Olympic Games in Tokyo Total daylight: 13:59hrs 24 July to 9 Aug Athletes: 138 Support staff: 60 Time zones crossed: 7 (W E) Hours difference: 7 Tokyo: 6am South Africa: 11pm Seasonal Change: (S N) PLANNING: Journey Melatonin & Cortisol Rhythms Diurnal Rhythms Sleep / Wake Rhythms Short stress of missing next flight, anxiety Flight choice Long fatigue, boredom, frustration ARRIVAL TIME FLIGHT HOME TIME TIME FROM TO LAY-OVER DESTINATION DURATION (SOUTH AFRICA) DIFFERENCE (TOKYO) Jhb Hong Kong 13 hrs 6 hrs 2 hrs 14.30 7.30 Hong Kong Tokyo Total4.30 flighthrs 7 hrs Jhb Singapore duration:10.30 hrs 6 hrs 2.40 hrs 17.35 10.35 Singapore Tokyo Approx.7 hrs 7 hrs Jhb Dubai 8.3018hrs hrs 2 hrs 1.50 hrs 15.55 8.55 Dubai Tokyo 10 hrs 7 hrs ✓ Eastward flight advance body clock ✓ Resynchronisation takes 1 day / time zone crossed Light exposure Light avoidance ✓ in the 6hrs after CBTmin ✓ in the 6hrs before CBTmin CBTmin ✓ 12h00 – 18h00 at destination ✓ 04h00 – 10h00 at destination ✓ sleep easiest @ low CBTmin ✓ approximately 3 – 6 am ✓ inter-individual difference CONCLUSION • Travel fatigue & jet lag potentially modifiable • Risk factors include: ✓ Physical fitness ✓ Time zones crossed ✓ Sleeping habits ✓ Age ✓ Flight direction ✓ Chronotype ✓ Previous experience ✓ Time at destination ✓ Sex • Many uncertainties on methods to advance or delay the body clock no cure yet (preserve sleep and alertness) • Environmental conditions need to receive attention • Illness preventative measures need to be in place • Meticulous planning! • Jet lag calculators: www.britishairways.com/travel/drsleep/public/en_gb www.jetlagrooster.com Correspondence: [email protected] Twitter: @ChristaJVR www.ioc-preventionconference.org/atpc2019/ CALL FOR ABSTRACTS & WORKSHOPS IS NOW OPEN Deadline: 15 September 2019 Submit your work on the website: www.ioc-preventionconference.org #IOCprev2020.