In order to run faster, it seems only logical that one should run more. But beyond the heart, legs and lungs, there is another group of muscles that can help you move ahead in the pack: the core.
"The core muscles are vital for runners," says senior physiotherapist Justin Wee, of Tan Tock Seng Hospital's Sports Medicine and Surgery Clinic. "A weak core usually translates to poor posture, which would affect running biomechanics. With runners, maintaining optimal running biomechanics may reduce injuries and optimise running performance."
The core muscles refer to the deep muscles of the trunk, he explains. They include the transversus abdominis, pelvic floor muscles, multifidus (a series of muscles attached to the spinal column) and diaphragm.
Six-pack abs, also known as the rectus abdominis muscles, are just superficial. You can have washboard abs that rival Hugh Jackman's but your core could still be weak, says Mr Wee.
"This is because visible six- pack abs simply mean that the individual has well-defined rectus abdominis muscles and a very low percentage of body fat," he says.
"Most of the core muscles are too deep to be visible."
Mr Derek Capps, group fitness instructor at Pure Fitness, says many runners often make the mistake of neglecting strength training. But for those who do strength training, many do not lift enough weight to produce muscle growth and benefit to the joints, and do not do enough core work.
"Runners may have a low body fat percentage but also lack lean muscle mass," says Mr Capps. "Runners often get lower back and hamstring injuries; core training can help you avoid them. It can also make you faster."
In a study published in 2009 in the Journal of Strength and Conditioning Research, a group of 28 recreational and competitive runners with an average age of 37 were split into two groups: One received a core strength training programme, while the other group had none. The programme consisted of five core-related exercises performed four times a week.
At the end of the six-week training period, there was a significant improvement in the core strength training group over 5,000m - by an average of 47 seconds.
"Core strength training may certainly be one of the causes of improved running times," say researchers Kimitake Sato and Monique Mokha, of the department of sport and exercise sciences at Barry University in Florida.
A weak core typically shows when fatigue sets in. Runners end up shuffling and slouching, placing stress on the hips, knees and shins.
Mr Wee says your core is probably strong enough if you are able to maintain a stable trunk with good posture comfortably while running, but also during other functional activities such as jumping, walking, and going up and down stairs.
Exercises that build a stronger core are those that challenge trunk stability. These include split squats, lunges, step-ups and step-downs, and standing on a wobble board, says Mr Wee.
"However, the amount of challenge an individual should work on should be carefully prescribed, as excessive or insufficient intensity would not be beneficial," he says.
Traditional movement like running, Mr Capps says, calls for traditional training. Based on that, he has devised this circuit of six exercises that feature ground-based lifts and multi-joint movements. "Ground-based lifts such as push-ups, squats and deadlifts teach the body how to give in and push away from the ground, just as in the running motion," Mr Capps explains.
"Multi-joint movement trains the core musculature and improves the transfer of power from arms to legs."
Week 6: Increase your intensity
National middle- and long-distance running head coach Ghana Segaran helps you stay on track for the ST Run.
After last week's easy sets, you should feel well-rested, and energised. Now, we will increase our intensity with only three more weeks before race day.
FOR 5KM RUNNERS
Tuesday - jog 800m (three sets)
This is your focus set of the week. Try this at a faster pace than you are used to. Rest one minute in between sets. You should be really tired at the end.
Thursday - jog 1km
Recovery day from the previous interval training.
Saturday - jog 3.5km
Run at a comfortable pace, focus on completing the distance.
FOR 10KM RUNNERS
Tuesday - 3km
Start off the week's sets with a hard run.
*Aim to go at 80 per cent of your maximum heart rate.
Thursday - 4km
Saturday - 10km
This is your trail run at race distance.
As this is your first attempt, take it easy and aim to complete the distance continuously.
FOR 15KM RUNNERS
Tuesday - 6km
Focus set of the week: Fast-paced run.
Thursday - 4km
Saturday - 14km
Take this as a confidence-building run.
*Aim to go at 70 per cent of your maximum heart rate.
*To estimate your maximum heart rate, take 220 minus your age in years.