HIIT (high instenisty interval training) is all the rage
Squeeze as much work into as shorter period of time as possible - you're in and out of the gym in 45 minutes including a shower and you can get on with the rest of your day.
HIIT training has it's place in any training program but it shouldn't be your sole style of training.
HIIT training can increase stress hormones released in your body
Increased Cortisol in the evening can disrupt your sleeping patterns, keeping you awake long into the night
Cortisol is responsible for regulating blood sugar levels - high levels of cortisol will react in the Liver communicating that you need to release glycogen (blood sugar) to escape from danger (fight or flight response)
Cortisol inhibits the release of Insulin from the Pancreas - so, once you have flooded your body with stored sugars you need to use them in your muscles otherwise your blood sugar will remain high
Cortisol encourages arteries to narrow - this will increase blood pressure - the goal of this is that blood (sugar/energy) will get to your muscles faster.
Don't get this wrong - cortisol is not your enemy, it is an important hormone in your body. It wakes you up in the morning, it responds to danger/fear, it controls your blood sugar levels.
HIIT training can increase the levels of Cortisol (which may be high due to stress anyway), which in turn can increase blood sugar levels - once these are used, your body will crave sugary food to replace what it has just used.
Unless you have planned a meal or good quality snack to have after your HIIT workout it's likely that you're reaching for a oversized (calorific) sugary (carbohydrate stacked) meal
Key tips to managing Cortisol
Mix up your workouts - within your week combine HIIT training and slower cardio and light weight training sessions
Aim to do your HIIT workout in the morning - Cortisol Levels are high then anyway, make the most of what is happening naturally in your body
Avoid stimulants like Caffine and High sugary foods
Adopt some regular low intensity exercise into your weekly routine e.g. slow running/walking (think marathon not sprint); some light yoga; pilates or movement practice (check out my movement program - free to move - it's free!)
My biggest bug bare with HIIT training - form and technique tend to go out of the window, speed and repetitions are the king in this style of training.
If your body has a compensation pattern i.e. does something that it shouldn't you are highly likely to be picking up injuries very soon.
Stress also has other effects on people - you've probably noticed if you are stressed at work that your shoulders will raise up towards your ears, you may get neck pain and/or headaches amongst numerous other symptoms.
If you consistently train to have high stress levels and your work/kids/partner/chores all give you high stress too then you are a ticking time bomb for poor sleep patterns, injury and pain.