TIME TO: BE YOUR BEST
WHAT DICTATES HOW MUCH YOU BENEFIT FROM YOUR COMMUTE, CLUB RIDE OR TURBO SESSION? FUELLING STR ATEGY? WEIGHT OF YOUR BIK E? FAT T Y DEPOSITS ON YOUR BACK? SCIENCE SUGGESTS IT ’S DOWN TO YOUR BIOLOGICAL CLOCK …
Your alarm clock pierces your ears, drilling into your synapses in a vain attempt to rouse you for the Saturday morning ride. It’s 7am, a hint of last night’s Proper Job nestles on your breath and your entire being’s in a state of turmoil as you force a grin to greet your clubmates. One of them – let’s call him Stanley Albert Utamol – woke up on the right side of his performanceboosting mattress and resembles an energy drink-fuelled kids’ TV presenter, rapidly reporting how wonderful he’s feeling. The conflict in moods carries over to the ride, ol’ Stanley and his fellow early birds leaving you and your fellow grumps lagging behind. It seems every single one of us has a peak time to pedal, where benefits are maximised and mood swings minimised.
“There’s increasing scientific evidence to support the informal concept of owls and larks,” explains Professor David Bishop, senior sports scientist at Victoria University, Australia, an authority on the subject. “It’s because most of our bodily processes vary over an approximate 24hour cycle, meaning we have mental and physical peaks and troughs.”
The idea that we peak at different parts of the day relates to our body clock or circadian rhythms. Circadian rhythms have been observed in animals, fungi and plants for years, and attracted major column inches last year when Americans Jeffrey Hall, Michael Rosbash and Michael Young won the Nobel Prize in Physiology and Medicine for their discovery of the molecular mechanisms that control the circadian rhythm.
You might think your Strava PB came down to ‘just feeling good on the day’ but check what time it happened. Your peak performance could have received a nudge from the brain’s circadian clock, as it regulates a staggering amount of processes that have a clear impact on your riding performance, shown below in brackets. These include dictating sleeping and feeding patterns (rest, repair and fuelling), alertness (descending), core body temperature (overheating or not), brainwave activity (pacing), hormone production (shift in speed), regulation of glucose and insulin (energy boost for the 10 per cent climb) and urine production (behind the bush, please). of which is daylight. Our in-built clock is actually a group of around 50,000 cells located in the hypothalamus part of the brain and is known as suprachiasmatic nucleus (SCN). The SCN receives illumination information through the eyes, specifically photosensitive cells called retinal ganglions. These have a direct line to the SCN, informing of light and darkness.
Based on this information, the SCN then switches the body’s state to consciously perform or rest thanks to key reactions including: stimulating the pineal gland in the brain to release melatonin – aka the sleep hormone; crank the body’s thermometer up or down; and control of the stress hormone, plasma. Those Nobel Prize winners dug a level deeper, identifying a ‘period’ gene that encodes a protein within the cell during the night that degrades during the day. This rises and falls throughout the day in a negative feedback loop, influencing behaviour and performance. It’s all very scientific, and all highly impacting on your ride.
“There’s no doubt that cycling performance changes throughout the day, ”says Bishop. “Studies have shown that measures of strength and power are greater in the afternoon or
evening than in the morning. In our own studies, we’ve shown that maximal sprint power is greater in the afternoon than in the morning. This coincides with a peak of body temperature, which increases factors such as nerve conduction velocity, flexibility and blood flow. Endurance performance seems to be less affected by time of day than power, although we’ve reported better endurance performance in the evening compared to the morning.”
In the study Bishop alludes to, nine recreational cyclists undertook four 1km time trials at different times of the day to see how time affected performance, pacing, and hormonal and metabolic responses. “On average, riders completed the time trials quicker in the evening,” explains Bishop, “though there was no difference in pacing strategy.” Bishop also observed important fitness parameters like oxygen uptake were also more efficient in the evening, while growth hormone and plasma glucose – both clear drivers of faster cycling – were also higher.
“There are actually limited studies into the impact of your body clock on sport,” says Bishop, “though another journal had subjects undertake exactly the same training for 10 weeks, but either in the morning (7-9am) or afternoon (5-7pm). The afternoon group enjoyed a 3.5 per cent increase in muscle size versus 2.7 per cent in the morning group.”
Your body clock is designed to keep you healthy with hormones like melatonin key to forcing you to sleep – for cyclists, time to repair and rebuild for the next ride – but it’s core body temperature that, as Bishop mentioned, truly impacts on cycling performance.
When Sir Bradley Wiggins smashed Alex Dowsett’s Hour record, increasing the world best from 52.937km to 54.526km, the velodrome temperature was set at 28°C. You ride faster in the heat because air is less dense than in the cold, but this wasn’t so hot that Wiggins would fatigue and lose power. It’s broadly the same concept with core temperature. Though it only varies by around 0.8°C throughout 24 hours, that’s enough to impact cycle-friendly variables like contractile force and cardiac output.
Luke Gupta, sleep expert at the English Institute of Sport, explains: “We all know about the midafternoon slump, but we incorrectly apportion it to digesting lunch. Our body temperature follows a distinct rhythm where it peaks in the early evening and hits a trough about two to three hours before you wake up in the morning. There’s also a small dip between the hours of 1 and 3pm. This drop in body temperature causes feelings of sleepiness, so if you’ve had a bad or shortened night’s sleep then feelings of tiredness during this period will be intensified. It’s also influenced by your chronotype…”
“STUDIES HAVE SHOWN THAT MEASURES OF STRENGTH AND POWER ARE GREATER IN THE AFTERNOON OR EVENING THAN IN THE MORNING” Professor David Bishop, senior sports scientist at Victoria University
introduced the concept of personalised sleep strategies to Team Sky. “Personally I’m a morning person. That’s when I might do more complex tasks like my business accounts. I tire in the afternoon so that’s when, ideally, I’d do simpler tasks like catching up with emails.”
‘Lark’ and ‘owl’ monikers derive from circadian rhythms not strictly adhering to the 24-hour clock; in fact, they vary slightly by individual with about an hour’s range from 23.8 hours to 24.8. This ‘slow’ or ‘fast’ clock relates to evening or morning types with reportedly 10 per cent qualifying as morning people, 20 per cent night owls and the rest in the large spectrum in between.
That time shift doesn’t sound huge but it has significant repercussions, with one study showing evening types can see performance levels drop by as much as 26 per cent when training in the morning compared to the evening. It’s why some suggest morning larks peak around noon, inbetweeners around 4pm and night owls around 8pm.
It’s an area that’s increasingly coming under the spotlight of elite sport. The 2013 Super Bowl champions Seattle Seahawks, for instance, made changes to training times and flight times off the back of determining their players’ chronotypes. As games reached the end, they knew which players would likely have the most energy to push on for victory. “There are studies that show training to suit your chronotype results in better sporting performance and fewer injuries,” adds Littlehales.
Your chronotype is a genetic trait and has the greatest impact on your circadian rhythm, with research suggesting up to 70 per cent of your day’s natural flow is dictated by genes. Those Zeitgebers then influence when you’re at your peak, but it’s not all about daylight as anything that might switch certain genes on and off can impact your body clock, such as exercise, food intake and ergogenics like caffeine. However, they tend to have more of an impact on secondary or peripheral biological clocks, in the liver, heart, muscles and lungs; some scientists think every single cell in our body features a biological clock.
Problems begin when your secondary biological clock ‘decouples’ from your primary one – the SCN. Tests on rodents who were fed the same calorie intake showed that nighttime feeders put on significantly more weight than the daytime feeders. They’d fought Mother Nature and expanded because of it.
So, your chronotype is important to peak cycling performance, but how do you find out yours? Anecdotally, we all know when we’re at our liveliest, though a host of online questionnaires attempt to intellectualise things. I completed one of the more credible, the awkwardly-titled Morningness-Eveningness questionnaire ( cet-surveys.com/index.php?sid=61524), and it showed that I’m a morning person. Which I’d agree with.
“THERE ARE STUDIES THAT SHOW TRAINING TO SUIT YOURCHRO NO TYPE RESULTS IN BETTER SPORTING PERFORMANCE AND FEWER INJURIES” Nick Littlehales, sleep consultant
So McCaugherty set about seeing how he’d react, behaviourally, emotionally and physiologically, to interval training, armed with a new turbo trainer, bike computer and heart rate monitor.
“I measured heart rate, cadence and speed as a proxy for power,” he says. The results? “In the morning my heart rate was a good 10-20bpm above where it was in the evening session even though my cadence was a lot slower, probably because my legs hadn’t woken up. My average speed for the session was a lot higher in the evening than the morning, too. Most importantly, I felt awful after the early morning session.
“I also considered recovery,” he continues. “The morning session ruined me for the rest of the day – mentally and physically I simply wasn’t ready for such an intense effort. In the evening I was able to have a good meal and head to bed to recover.”
So, has the experience changed the way he rides? “Absolutely. During the working week I only ride hard in the evenings, which has the advantage of my bike commute home providing a warm-up for the session ahead. At weekends I used to always get up at dawn but now I’ll rarely get up for an early spin, even with my club. In fact, we’ve started an alternate later ride, which has become popular with those who like a liein and have the luxury to fit life around cycling rather than the other way around.”
What does this mean to you, the super-keen recreational rider? We’ll focus on the inbetweeners as that’s most of you. When it comes to club rides, unless you have the persuasive powers of McCaugherty, stick with the morning. Just be aware that your circadian clock will appreciate a low- to moderate-intensity (you can chat) effort. That said, with blood-glucose levels lower, there’s an argument that this is the time to maximise fat-burning fasted rides.
Come those interval efforts to boost power, aim for around 4-7pm, while a nod to the positive impact of blue light means you might want to maximise off-season efforts or late spring efforts aboard a turbo trainer in front of a lightbox like those from Lumie. Those dawn-light simulators also come in handy to awake owls, says Littlehales. Don’t consistently eat too late or you’ll uncouple your clocks, but as research suggests a late 20g hit of protein benefits muscle repair and growth, the occasional shake won’t do any harm.
As for the future, back to Bishop. “You’ll see a lot more research into how circadian rhythms affect biology. My guess is that the most interesting will be how disrupted circadian rhythms (for example, jet lag, insufficient sleep…) affect biological processes and what can be done to counteract these effects. I think you’ll probably see some hype about ‘the best time to cycle based on your chronotype’, but my guess is a lot of this will be exaggerated. Still, if your training, nutrition and recovery are good, I would suggest experimenting with what time of the day you train.”
“THE MORNING SESSION RUINED ME FOR THE REST OF THE DAY MENTALLY AND PHYSICALLY I WASN’ T READY FOR SUCH AN INTENSE EFFORT” Simon M cC aug her ty, Human Cyclist blogger