Yesterday, I did a 93 mile ride and it was split in two halves. The first half of the ride was really enjoyable as I felt strong and maintained a good pace. After about 3 hours (50 miles) it was completely different. My legs felt heavy and I really started to struggle so the second half of the ride was the complete opposite of the first part. I tired so much that I was desperate to get home – if someone had offered me a lift I would have probably taken it. So, why did a good ride suddenly turn so bad?
The only explanation for the sudden change is that I ran out of energy. I’d had a good breakfast and I had eaten two small bags of dried/fruits/nuts along with drinking two bottles of my own energy drinks. I’m going to assume there was 35g carbs in the fruit nuts and 15g carbs in the energy drinks. Therefore, total carbs would have been 35 x 2 plus 15 x 2 = 100g = 400 calories. The maximum carbs the body can consume is 1g per minute, therefore after 3 hours I could have consumed 180g carbs (3hrs or 180 minutes x 1g). This would have meant I could have consumed another 80g carbs or 320 calories by the time I had ridden three hours. Therefore, by this point I was riding in deficit according to the nutrition I required.
The sudden change is explained by all my blood glucose and glycogen stores being depleted and my energy needs were then completely dependent on what I could consume. In addition, I had been restricting my calorie intake as a means of losing weight. This no doubt meant that my stored muscle and liver glycogen were not optimised for longer rides. The maximum I can store is likely to be around 500g (400g in muscles and 100g in the liver) which equates to 1600-2000 calories. At 50 miles I knew that my energy supplies had been depleted. If I assume a maximum glycogen storage of 1600 cals I can roughly calculate what I had stored prior to the ride based on what I consumed before and during the ride:
Breakfast 800 cals, Consumed on ride up to 50 miles 400 cals, Total 1200 cals
At 50 miles my body would have consumed 1750 cals, therefore, my stored glycogen would have been 1750 cals – 1200 cals = 550 cals which is a third of what it could have been. In other words, the reason I bonked was primarily due to my glycogen stores not being at full capacity. This therefore begs the question as to whether calorie reduction is the best way of losing body fat.
Based on a weekly activity of 8.5 hours my daily carb requirements are 6g per kg body weight (ie.6×70=420g). I was eating no more than 200g carbs per day. Actually, it would have been a lot less than this as I was weighing 50g of rice or pasta and using this weight as my total carb intake. I reality 50g of rice or pasta deliver less carbs than this, probably 35g or carbs. Therefore, I have been eating a very low carb and low calorie diet. Therefore, in reality I was running on near empty when I went on my long ride so it was going to be inevitable that I bonked.
Ultimately, I need to train to get stronger and this requires me to consume sufficient calories to support this. I want to feel strong when I am out training as it provides a psychological boost and motivates me to train more. I have managed to control what I eat but I am clearly eating less than I need. I have also risked losing muscle mass. Therefore, I will increase my calorie consumption by eating more carbohydrates. I will eat approx 350g carbohydrates per day which equates to 1400 cals.
Due to feeling hungry I have been unable to go to bed without having a meal. This is not ideal so by consuming more calories during the day I will try to cut off the need to eat before I go to bed. I will also increase my training workload to 4/5 sessions per week to reduce my body weight. I have had enough of calorie restriction – it is just counter-productive. I’ll let my body get rid of the excess fat through training.
In summary, the lesson I have taken away from yesterdays long ride is that it was most likely depleted glycogen stores that led to me bonking as opposed to not consuming enough food before and during the ride.