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Jet lag’s impact on athlete performance: Part 3

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In Part 1 and Part 2 we discussed what jet lag was and how athletes can incorporate simple interventions to help cope with the symptoms of phase advances and delays. In Part three we will outline strategies for time-zone shifting and provide advice on designing a comprehensive time-zone management plan. Specifically, pre-travel activities, in-flight activities, and post-flight activities will be discussed, as well as a sample of a time-zone equivalence table to help visualize what’s involved in a time-zone management plan.

Pre-travel sleep history

Ideally, athletes and support staff will have the ability to monitor sleep schedules and sleep quality at least a month prior to travel. This way, athletes who are having issues with sleep can be identified and more rigorous schedules and interventions can be implemented.

For example, a time-zone management strategy for an athlete that naturally falls asleep at 11:00pm and wakes up at 7:00pm with no sleep disturbances is going to look quite different compared to an athlete who falls asleep at 1:00am, wakes up several times during the night, and rises at 9:00am. Recording an athlete’s sleep history and habits can help support staff design an efficient and realistic time-zone strategy for individual.

Pre-flight adaptation

According to Dr. Charles Samuels, the Medical Director of the Centre for Sleep and Human Performance in Calgary, preflight adaptation should begin at least 7 days before travel aoccurs (2012). Several strategies include: reducing training volume and intensity, adjust training to the destination time zone, and choosing an evening flight for travel eastward (reduced light will make it easier for athlete’s to synchronize their rhythms with a phase advance).

Samuels also notes that endurance training should be modified to reduce volume, intensity and frequency, and that coaches should weigh the benefits and risks associated with training before travel.

In-flight activities

It’s recommended that athletes switch their watches to the destination time as soon as they board the plane. This helps them prepare and adapt for the destination. The environment should be comfortable – using pillows and supports while minimizing distractions is crucial. It’s also been shown that feeding at the appropriate times can dramatically improve circadian adaptation (Reilly 2007). Athletes should eat according to the destination times and make sure they are well hydrated throughout the entire flight.

Finally, this is the time in which athletes and support staff will want to start providing interventions such as eyeshades, ear-plugs, melatonin, caffeine, or light-emitting devices (according to the direction of travel and the athlete’s time-zone management plan).

Post-flight activities

For 2-4 days after travel, the activities of the athlete should be closely monitored and planned by support staff to ensure a quick adjustment to the new time zone. Their rest, sleep, meals, training, and recovery should all be taken into account when developing a post-flight strategy. As we mentioned in Part 2, a combination of light therapy, light avoidance, caffeine, Ambien, and melatonin can be used during these first few arrival days to help the athlete adjust faster.

Time-zone equivalence tables

Combining all these elements can get a little tricky at times. But, as Dr. Caldwell (2015) mentions, one of the most helpful aids for circadian adaptation are time-zone equivalence tables. These tables include time-zones for both the departure city and the arrival city, the scheduled event time, a personalized sleep schedule, and any interventions needed pre, during, and post travel. You can view a sample of the table below (taken from Dr. Caldwell’s paper titled Strategies for Time-Zone Adjustment for Athletes).

In this example, a team of runners from San Francisco are travelling to New York for a competition. You can see the interventions laid out and the strategy for helping them adjust to the phase advance. These interventions, combined with the careful planning of the support staff, helps the runners quickly adapt to a 3-hour time shift so they wouldn’t experience any performance issues.

Impact on athlete performance Time Equivalents between San Francisco and New York

Planning an individualized time-zone management strategy for each athlete is critical for maximizing performance. By taking a close look at an athlete’s sleep history and by carefully monitoring preflight, inflight and post flight activities, support staff and coaches can drastically minimize the effects of jet lag and significantly increase success during the event.

References

Dr. Caldwell. Strategies for Time-Zone Adjustment for Athletes

Reilly T, Waterhouse J, Burke LM, et al. Nutrition for travel

Samuels C. Jet lag and travel fatigue: A comprehensive management plan for sport medicine physicians and high-performance support teams

Jet lag’s impact on athlete performance: Part 2

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In an effort to reduce fatigue and minimize the effects of jet lag, The Union of Sports Ministry in India recently made the decision to send their athletes to Rio for the 2016 Olympics a full month before the Games. In previous Olympic games, athletes were arriving as close to 2 days before their scheduled events. This focus on body-clock synchronization speaks to the effects of jet lag on athletic performance.

In Part 1 of this three part series, we focused on defining jet lag, the exact mechanisms involved, and how it affects an athlete’s performance. This post will explore some of the most effective intervention techniques designed and proven to help cope with jet lag.

Light exposure

One of the factors that should be the most closely monitored is an athlete’s exposure to light when traveling through different time zones. In humans, light is strongly linked with an alert or wakeful state, and it acts as the most potent circadian phase shifter (Cajochen, 2007).

There are two different types of phase shifts – phase advance (moving everything earlier in the body-clock’s day), and phase delay (moving everything later in the body-clock’s day). As you can see in the table below, an athlete’s exposure to light will depend on what direction they’re traveling, and how many time zones they’re crossing.

When an athlete travels from west to east, their body is going through a phase advance – which means they need to shift to an earlier time zone. In this case, the athlete should be exposed to more light in the morning and less light in the afternoon. When traveling from east to west, the body is going through a phase delay and shifting to a later time zone. Conversely, light should be minimized in the morning and maximized in the afternoon.

There are several strategies for increasing and decreasing light exposure during long trips: Seasonal Affective Disorder light devices (450-480nm) at approximately 1500 lux are perfect for maximizing light exposure, and light-blocking glasses that have been created to block between 80% and 98% of incident light in the blue range work to minimize light exposure (Samuels, 2012). Ideally these interventions should be implemented 2-3 days before the time-zone shift.

 

Jet Lag impact on athlete performance Fatigue Management Intervention Strategies

Melatonin

The effects of melatonin on athletes traveling through multiple time-zones is well-studied, and it has been proven to have a mitigating effect on jet lag symptoms (Manfredini, et al 1998). Melatonin is a hormone that is known as a chronobiotic drug, or a drug that specifically affects an aspect of one’s biological time structure. Produced by the pineal gland during darkness (and therefore usually at night), melatonin is responsible for the synchronization of the circadian rhythms.

Several studies have demonstrated the efficacy of well-timed, low dose of melatonin to overcome the symptoms of jet lag (Cardinali et al. 2002, Manfredini et al. 1998, Parry 2002). Most experts agree that <1 mg is sufficient to shift human rhythms (any more seems to have a lethargic effect – not something you want to induce in high-level athletes). The general rule is evening administration advances one’s body clock (induces sleepiness) and morning administration delays it (helps keep you awake). Using melatonin to fight jet lag works best if it is consumed 30 minutes before/after the athlete’s normal sleep/wake cycle, and taken at least three days after the time-zone shift (Samuels, 2012).

Caffeine

Just as melatonin is used to help induce an athlete’s natural sleep rhythms, caffeine is used to help an athlete maintain alertness when their body’s clock is telling them it’s time to sleep. In a study by Dr. Beaumont titled Caffeine or melatonin effects on sleep and sleepiness after rapid eastward transmeridian travel (2004), it was found that slow-release caffeine reduced sleepiness for a few days after travel and helped alleviate symptoms of eastbound jet lag.

The recommended dose of caffeine is 100-300mg every four hours, and should not to be taken too close to the destination bedtime (Caldwell, 2015). Some of the most effective sources of caffeine are: NoDoz© (100-200mg caffeine), home-brewed coffee (100 mg per cup), Red Bull© (83 mg per can), 5-Hour Energy© (215 mg per bottle) and Coca Cola© (34 mg per can). See Table 1 for the recommended dose of caffeine depending on the direction of travel and the number of time-zones crossed.

Ambien

The final pharmacological intervention used to fight jet lag is Ambien. The recommended dose of Ambien (10mg) taken right before the standard local bedtime, can help athletes fall asleep when their internal body clock is telling them to remain awake. This sleep medication is short acting, produces no side-effects, and can be used during the first 2-3 days in a new time zone (Caldwell, 2015). Athletes should always consult a medical professional when deciding if Ambien is right for them or not.

As with other sports performance techniques, the modification and scheduling of these intervention techniques should be tailored to the athlete’s lifestyle, body composition, reactivity to stimulants, and medical history. Though the symptoms of jet-lag are unavoidable, using integrative and personalized intervention techniques can significantly help athletes cope with the unwanted effects.

In Part 3 of this series we’ll talk about some important strategies for time-zone shifting. Stay tuned.

References

Cardinali D, Bortman P, Liotta G, Lloret S, Albornoz L, Cutrera R, Batista J, Gallo P (2002) A multifactorial approach employing melatonin to accelerate resynchronization of sleep-wake cycle after a 12 time-zone westerly transmeridian flight in elite soccer athletes.

Manfredini R, Manfredini F, Conconi F (2000) Standard Melatonin Intake and Circadian Rhythms of Elite Athletes after a Transmeridian Flight.

Manfredini R, Manfredini F, Fersini C, Conconi F (1988) Circadian rhythms, athletic performance, and jet lag.

Parry B (2002) Jet Lag: minimizing it’s effects with critically timed bright light and melatonin administration.

Samuels C.H. (2012) Jet Lag and Travel Fatigue: A Comprehensive Management Plan for Sport Medicine Physicians and High-Performance Support Teams. 

Jet lag’s impact on athlete performance: Part 1

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Today, professional athletes are frequent flyers. And, rapid time-zone changes can pose serious challenges to their competitive edge. This 3-part series introduces strategies to combat the effects of jet lag on pro athletes.

Jet lag defined

Humans have a number of internal physiological processes that are normally tuned to a well-synchronized 24-hour rhythm that’s regulated by the timing of sunlight exposure. When your schedule is consistent, in terms of morning wake ups, daytime activity, and nightly bedtimes, your body’s time and the environmental time are closely aligned, and thus your body’s rhythms are in harmony. Whenever 3 or more time zones are crossed, however, disagreements between the body’s internal clock (your body’s sense of time) and the clock on the wall (the time cues in your new environment) can wreak havoc if not properly managed. Since this is a phenomenon made possible by modern airline transportation, it has been labeled “jet lag.” In addition to changing time zones, all the other hassles that accompany traveling by air (check-in procedures, seating conditions, schedule delays, high altitudes, dry air, etc.), only make matters worse.

Jet lag symptoms

Typical symptoms of jet lag include sleep disruptions, altered mood, loss of appetite, stomach upset, disorientation, and generalized discomfort—all of which can be traced directly to desynchronization of the body’s internal rhythms. And of course, the more time zones crossed, the more severe the symptoms.

Fact or Fiction: The direction of travel makes a difference

Fact. Jet lag is much less of a problem after travelling in a westward direction than an eastward direction because it is always easier to shift the body to a later schedule than an earlier one. Think about it, people have little difficulty staying awake a little longer than usual (and sleeping in later than usual) on days off, and this is exactly what happens when traveling west where everything occurs later than in your home time zone. But in the case of eastward travel, forcing yourself to go to bed earlier rarely leads to actually falling asleep earlier than usual, and waking up at 3:00 or 4:00 in the morning is never fun. Heading eastward shifts everything ahead of schedule, and the body definitely doesn’t like this change. In both cases, however, the body’s clock resists any disruption, and thus it takes time to readjust: at least one day per time zone crossed.

Jet lag and the athlete

Athletes need to be aware of an additional jet lag factor that can especially interfere with their performance: timing misalignment. On top of the “internal body-clock desynchronization” described above, a misalignment between body-clock time and local-clock performance time can create problems even when jet lag symptoms are minimal. Such is often the case when only 3 time zones are crossed.

There’s a rhythm to sports performance that favours late-afternoons and early evenings, and moving the competition away from these times (according to the body’s internal clock) can lead to unfavourable results. This explains why west coast teams have an advantage when playing nighttime games on the east coast. A 9:00pm game in the east occurs at the west coast team’s body-clock time of only 6:00pm, which is a time of day when athletic performance is enhanced. In an article on circadian rhythms, athletic performance and jet lag, Dr. Roberto Manfredini and his team cite considerable evidence that sports performance peaks around 1600 to 2000 hours when reaction time is faster, grip and back strength are stronger, flexion is greater, exercise endurance is longer, and the perception of physical exertion is lower than it is earlier in the day. In addition, there’s typically less joint stiffness and reduced pain perception in the early evening than in the morning.

Of course not every type of performance is best later in the day peaks in the evening. While reaction time tends to be faster at the timing of peak physical capability, Accuracy, at least on some tasks, is worse than it is better earlier in the day. Thus, it is suggested that earlier times of day may be better for sports that demand accuracy and implementation of competitive strategies, and for the delivery and recall of coaching instructions.  However, in general, physical performance is better when body temperature is relatively high versus low, and this happens in the early evening according to the body’s internal clock.

 

Jet lag and the athlete

Figure 1. From Duffy JF et al (1998) Core (rectal) body temperatures for young and older subjects. Solid orange circles = older subjects; open grey circles = younger subjects; Solid bar = usual sleep episode of older subjects; open bar = usual sleep episode of young subjects.

 

Traveling can be adversarial for athletes due to:

  1. trip-related fatigue and stress
  2. time-zone related desynchronization of the body’s internal rhythms, and
  3. time-zone related misalignment between the body’s peak capabilities and the local timing of performance requirements.

The bad news is that there’s no “magic bullet” that can wipe away these problems. The good news is that there are science-based strategies to mitigate their effects.

Check out Part 2 and Part 3.

References

Smith RS, Guilleminault C, and Efron B (1997). Circadian rhythms and enhanced athletic performance in the National Football League

Manfredini R, Manfredini F, Fersini C, and Conconi F (1998). Circadian rhythms, athletic performance, and jet lag

Duffy JF, Dijk DJ, Hall EF, and Czeisler CA (1999). Relationship of endogenous circadian melatonin and temperature rhythms to self-reported preference for morning or evening activity in young and older people