The standard formula for calculating one's maximum heart rate is "220 minus your age". But experts suggest the textbook is wrong: everyone's maximums, from heart rate to output, are different. Understanding yours is the key to peak performance.
To learn how to unlock my potential for next year's Standard Chartered Hong Kong Marathon, I meet Dr Michael Tse from the Active Health Clinic and University of Hong Kong's Institute of Human Performance. Tse is a former trainer and performance consultant to many of the territory's elite athletes.
A number of factors make a great runner, he says, including body composition, running mechanics and strength. "But when you're starting out, what you really want to know to become a faster, more economical distance runner, is how to benchmark your fitness. Doing so allows you to see your inherent ability, as well as what sort of training will help you."
There are two measurements that are key, says Tse. First, VO2 max, or the maximum capacity of your body to transport and utilise oxygen to fuel muscle movement. (Think of it as the size of your "engine".) Second, the lactate threshold, which is the point where pushing yourself harder becomes counterproductive during a long-distance race.
Knowing your VO2 max gives you a good indicator of your condition and shows you where you can push the boundaries of your training to improve.
Next, as running intensity increases, you produce lactate in the blood. Lactate (or more accurately, its negative by-product) is responsible for that burning sensation in your legs when running. While the good news is your body is pretty effective at processing lactate, there's a point where its production exceeds its removal: the "lactate threshold". It's the point where fatigue sets in.
Making sure you work up to, but not past, your threshold during a marathon race is essential for lasting the 42.195-kilometre distance. During training, working above and below your thresholds will help to boost your speed.
There are many ways to calculate your VO2 max, from a simple formula that uses resting heart rate and age to the Rockport Fitness 1.6-kilometre Walking Test. Just Google "calculate VO2 max" and you'll find a range of online calculators.
But the most accurate VO2 max measurement is done in the lab - and so I was tested by exercise physiologist Glen Joe at the Institute of Human Performance.
Wearing a gas mask that vaguely looks like something from a Swat team, I ran on a treadmill at increasing speeds while Joe recorded the oxygen and carbon dioxide content of the air I breathe in and out.
I'm pleased to find out that my VO2 max is 51.7 millilitres of oxygen consumed per kilogram of body weight per minute (ml/kg/min), putting me in an "elite" category for my age. In comparison, the late Norwegian marathon world champion Grete Waitz had a VO2 max of 73.5, the legendary Steve Prefontaine 84.4, and three-time Tour de France winner Greg LeMond 92.5.
While my results reflect the training I have already put in, a good VO2 max also reflects genetics.
My max heart rate is also high - recorded at 197 beats per minute - although both Joe and Tse believe I could have pushed it harder.
For runners with a lower VO2 max, Tse recommends building a fitness foundation. "You need to go back to basics and build up a base at lower intensities," he says. This means being disciplined with slow runs, and resisting temptation to go hard and fast every time you ride an endorphin high.
Conversely, better-trained runners who want to improve need to do some high-intensity training.
Tse's advice reinforces the importance of the speed work coach Clinton Mackevicius has included in my training plan. The key to a faster marathon, says Tse, is to train the body to shift your lactate threshold to occur at higher speeds. During my treadmill test, Joe also checks my blood lactate at each stage with a small finger prick.
Results show my lactate threshold occurs at 90 per cent of my VO2 max, meaning I can run up to 90 per cent of my capacity in an aerobic zone before relying on my anaerobic system. According to Tse, I am pretty efficient.
To optimally change your lactate threshold requires a periodised training programme, similar to what Mackevicius has devised for me. It should include base aerobic work, tempo runs below and around the lactate threshold, and interval running to train the body to tolerate lactate accumulation and facilitate its removal.
I was also tested on the clinic's DEXA scanner, the gold standard for measuring body composition and bone density.
While my body fat percentage could go down (it is 27 per cent, which is in the healthy range of between 21 and 33 per cent by World Health Organisation guidelines), real improvements could be made in my muscle mass, which was slightly lower than average.
"As a runner you want to reduce fat weight, which has little metabolic benefit compared to muscle," says Tse. He recommended a variety of strength exercises to help stimulate and grow my muscles.
"Whatever [fat] you can lose, without going overboard, and while remaining healthy, may be of benefit to running performance," he says.
Time to cut out the post-run indulgences, it seems.
Marathon Mania is a 12-week series leading up to the Hong Kong Marathon on February 24. For more preparation tips, go to facebook.com/hkmarathon
Peak performance factors and how to improve them.
- VO2 max: base level aerobic training and some running at VO2 max pace.
- Lactate threshold: some running efforts at and around lactate threshold pace.
- Body composition: reduce body fat within reason to carry less "useless" weight.
- Running mechanics: proper mid-foot strike and higher running cadence; about 180 steps per minute.
- Strength and injury prevention: running is weight-bearing exercise. Building strength can help you perform better, recover quicker and reduce injuries
Rachel's training diary:
While I mixed up the order of my runs this week, I still managed a speed session, threshold run, a few shorter runs and a long run. Two weeks in and feeling good.
It was all about my running buddies this week: they pushed me hard along Bowen Road, stopping me from giving up on my sixth rep when I was spent, and kept me going on my long run when I wanted to opt for brunch. If any of you are struggling, enlist a friend.
I have become slack with my running drills, but I bought some training cones for motivation. Let's hope they work next week.