Blog Port Hills Ultra 50km 2021

Port Hills Ultra 50km 2021

January 30, 2021

Talk about Christchurch runners being spoilt for choice! After participating in the inaugural Aotearoa Ultra three weeks prior, I was lucky enough to back this up with another inaugural Christchurch event – the Port Hills Ultra. Having run in the Port Hills a few times, I was aware of how challenging the terrain could be so I choose the safe 50km option (21km, 75km, and 100km distances also on offer). Although well accustomed to the Port Hills, I was quite keen to learn a few new running tracks to add to my trail running bank. The race started at 10am at Victoria Park so for once I was able to enjoy a relative sleep in and an unrushed breakfast. As Victoria Park was 25 minutes away, it was also only a short drive to the start line. This was all a novelty of course as early starts and bus trips to the start tend to be the norm in ultra running. The latish start also meant that I was accompanied by my wife and two young girls which is a rare treat. When we arrived at the start line, we were greeted by just over 20 runners and a sprinkling of supporters. Some runners already had their poles out in preparation for the notable 3000m total elevation gain. After a few rushed photos, it wasn’t long before my kids lost interest in the ‘colourful people carrying sticks’. They waved goodbye and rushed off to the kid’s playground in the distance. My inner child smiled. “I’ll try be back around 6pm”, I tell my wife. I turn away and slowly jog towards my own, much larger playground in the hills.

With my two girls at the start line (Millie – left & Poppi – right)

Running in the Port Hills is like going to your favourite restaurant. Most of the time you order the tried and trusted but other times, you want to try something different. The tried and trusted for most runners for many years has been a high carbohydrate (HCHO) diet. Carbs have been shown to enhance performance in exercise greater than 60-90 minutes and carbo-loading 24-36 hours pre-race is a common practice in running circles. So what’s with the sudden interest in a ketogenic aka low carb high fat (LCHF) diet (defined as < 50g of CHO/day with fat providing 75-80% of energy compared to a HCHO diet where carbs provide 60-65% of energy)? As mentioned in my last blog, a LCHF diet can provide beneficial short term health benefits for some people and particularly those with type II diabetes. But are there any performance benefits from a LCHF diet? Should all ultra distance runners be on a LCHF diet? The rationale being that a high fat diet increases our capacity to use fat as an exercise fuel. We also have unlimited fat fuel stores compared to our limited liver and muscle glycogen carbohydrate reserves. An advantage of preferentially burning fat may therefore mean that you won’t need as much carbohydrate during an event. However, often refuelling during an event is not a problem anyway due to the availability of aid stations. The idea of a LCHF diet was first raised in a study by Phinney et al in 1983. Phinney showed that endurance trained cyclists (n=5) who ate a ketogenic diet for 4 weeks had no compromise in endurance exercise compared to a ‘balanced diet’ with both groups having a similar exercise endurance of 2.5 hours on an ergometer (i.e. no actual performance benefit – just parity). This idea of a LCHF diet is therefore nothing new and there have been a few more studies since. So why the sudden explosion in interest? The answer lies in n=1 and social media. The best marketing study of all. Get a LCHF runner with great genetics who wins a race, looks the part, and has a following on social media and BINGO. Everyone should now be on a LCHF diet and they too will win races! As mentioned in my last blog, good nutritional studies are hard to come by. Often study participants self-select their diets and recording exactly what people eat is tedious and challenging. So I thought a recent study by Burke et al (2020) gave a good attempt of answering this question utilising a well designed scientific study. A sample of 26 male and female elite race walkers had energy matched LCHF and HCHO diets for 25 days and the same three week training program. Both groups were matched for age, body mass, base line VO2 max, and personal bests so there were no significant differences between both groups other than the diet they were eating. When both groups were retested over a 10 000m race walk, the HCHO group improved by 5% and LCHF group were slower by 2%. So in this group of elite walkers, a LCHF diet was actually detrimental to their performance. The critics will say a 10 000m race is not long enough or that fat adaptation for performance benefits take “several months” (i.e. 4-6 months) and not 2-3 weeks. To which I look forward to their long term studies on compliant ultra runners (whom in my experience tend to follow their own path and do what they want anyway). So once again we fall back on the need for more research on the performance (and health) benefits of longer term fat adaptation. Also, remember that the Burke et al study involved elite trained athletes. Thereby, if you were to start eating a LCHF diet in addition to exercising/training, there’s a good chance that you’ll shift some weight (which LCHF diets and exercise are known to do), and by default you’ll get a ‘performance effect’! But all things being matched, if you’re a well trained athlete at optimum weight who is performing well on a HCHO diet, then the evidence isn’t compelling to switch to a LCHF diet. So what do we believe is the science underpinning this finding? We know that although fat provides more energy than carbohydrates, the body requires more oxygen to burn fat compared to carbohydrates. That is, to produce the same speed/intensity/power from burning fat, you need to use a higher fraction of your VO2 max which by definition reduces your exercise economy (exercise economy has been shown to correlate better with performance than VO2 max). Now, this may not be an issue when oxygen is plentiful (e.g. sea level compared to altitude [note that a HCHO diet is also recommended in high altitude]) or when the demand for oxygen is low (e.g. low intensity compared to high intensity exercise). In other words, a LCHF diet may not be a problem for sports that require moderate aerobic intensity (e.g. 60-70% VO2 max) as there’s more aerobic reserve at lower intensities / extra wiggle room. But it could become a problem for athletes exercising at higher intensities (e.g. 80-90% VO2 max) and exercising at higher intensities is critical for elite athletes. So, the current scientific consensus is that a LCHF diet does not translate to improved performance in sports in which athletes need to work at higher intensities, speeds, or power for the above reasons. But a LCHF diet may still have some potential in recreational endurance runners participating at medium to low intensities. That is, those running long distances at conversational pace which are most of your middle of the pack runners and plodders. Where do I stand on this? I’m biased by my upbringing. My father is a Kiwi and my mother is a Filipino. Whilst growing up, to keep the peace and both parties happy, I learnt that I needed to eat potatoes AND rice. So now, I routinely double carb for most of my meals and as a result, I’m intermittently vilified. But I do like this concept of “metabolic flexibility” – using a variety of energy generating pathways. That is, why should we only be good at burning fat or carbs? Why can’t we be good at burning both? After all, you’re predominantly priming your fat burning pathways when you go for a morning run before you eat breakfast. Why get all worked up about fat versus carbs? Why can’t our energy systems cooperate and we all just get along? Why can’t I just eat my potatoes and rice in peace?

Ready to go bush. Heading into Kennedys Bush Reserve

The beginning of the Port Hills Ultra serves a familiar menu in the form of the Harry Elm track and the Crater Rim Walkway south of the Sign of the Kiwi. The course then veers off downwards towards the South Boundary Track along Faulkners Track which is all new to me and proves to be quite technical. The next section along Watlings/Bush Rd/O’Farrells/Cass Ridge Track is more unventured territory until I link up with the familiar Sign of the Bellbird. Although I’ve run past Kennedys Reserve a number of times, I’ve never really stopped to explore it so the Orongomai Trail loop was a highlight. This was pure running soul food as one was completely surrounded by dense beautiful native bush despite being so close to the city. We reconnect with the Crater Rim Walkway again and head towards Sugerloaf via Mitchells Track which offers some nice harbour views. I make good progress along Latters Spur Track which is an easy going pine needled downhill track but this marks the end of the honeymoon phase. From here, the leisurely 10am start begins to take its toll. The heat of the day starts to bite as we ascend up Hidden Valley Track and back towards Sugerloaf for the second time. I manage to link up with another runner who has a similar pace to me (Josie originally from Wales) and our conversation provides a welcome distraction to the heat and the uphill grind. We’re back on familiar tracks along Farm Track and the Mt Vernon Valley Track but the event organiser adds a cruel twist by directing runners into more unchartered territory – unheralded farmland by name of Linda Woods Reserve. Why bother going up the perfectly formed Rapaki Track when you can venture along sporadic sheep tracks whilst practising orienteering (without maps) all the way to the top of the Summit Road? Josie and I manage to successfully stay on course and we replenish at the final aid station at the top of the Bridle Path. From there, it is a 12km push back past Castle Rock via mountain bike tracks until we connect with the Harry Elm Track again and head back towards the finish at Victoria Park. I cross the finish line just after 6pm, 8 hours and 10 mins later. Tired but not exhausted. Legs appropriately primed for bigger things. If the Port Hills Ultra was the appetiser, then the Tarawera 100 miler in mid February is the main course. Running is medicine. Join me at my next blog, the Tarawera 100 miler (165km). Hopefully I haven’t bitten off more than I can chew.

That was tough. Crossing the finish line at Victoria Park

Helpful tip
Practise “metabolic flexibility” in your training so you can use a variety of energy generating pathways