Marathon-pace training is one of the best workouts there is for improving the endurance capacity of slow-twitch, endurance muscle cells, said coach and author of Build Your Running Body Pete Magill.

This style of training, Magill said, increases aerobic energy production, builds more capillaries to carry more oxygen to the slow-twitch cells, improves the cells' ability to export lactate and reduce acidity, and leads to better running economy.

According to Chris Solinsky, a former US record holder, marathon-pace runs teach a person to read their body and learn to find a pace that is tough but that can be sustained.

"Marathon pace runs help build a strong foundation in which to introduce interval training to get through your racing season," Solinsky said.

"The stronger the foundation, the better interval work you can do, which leads to knocking many seconds or minutes off of your times."

If you don't have a good idea of your current marathon pace, Magill recommends sub-20 minute 5km runners aim for 28 to 31 seconds slower per kilometre than current pace, and slower runners add 38 seconds per kilometre to their current pace. He calls this effort level "slow tempo", because it's faster than your normal run pace but slower than 15km to half marathon race pace, the speed usually recommended for tempo runs.

"If you're new to the sport or out of shape, your marathon pace for training purposes might only be a little faster than your regular distance pace," Magill said.

"If that's the case, use your breathing rate as a guide. For distance runs, your effort should always be conversational. At marathon pace, your breathing noticeably quickens and conversation beyond a few, curt two- or three-word responses is uncomfortable."

A marathon-pace session should provide an endurance boost that complements faster running and gives an ability to sustain high-quality performance over a long racing season.

"Rather than pummel your body with hard intervals following a race weekend, a gentle session of two or three 10-minute repetitions at marathon pace, with a couple of minutes of jogging between reps, helps to reinforce the fitness gains of previous weeks without overloading your fatigued nervous system, energy system, or faster muscle fibres," he said.

For more continuous marathon-pace runs, Solinsky advised going for one-third to two-thirds the distance of your current long run. "So if you are doing a 24km long run, you would do a marathon-pace run for eight to 16kms," he said.

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Plan an easy run on the days before and after a marathon-pace run.

"This is definitely a hard day," Magill said. "Even though the workout is energising and should never result in significant fatigue, it's still a drain on your nervous system and muscle glycogen stores, as well as an increased strain on your muscles and connective tissue."

As on other hard days, include a warm up and cool down. But because the pace is slower than you run on interval workouts and tempo runs, a relatively short warm up, of 10 to 15 minutes of easy running, should be sufficient. Similarly, a short cool down of a couple of kms or 10 minutes is enough.

One other great thing about marathon-pace runs - they're convenient. Instead of going to the track or another place conducive to repeats at 5km pace, you can simply head out on one of your favourite loops. Use the couple of kilometres as a warm up, then get rolling at marathon pace and return home a better runner.