# High Intensity Interval Training Explained ## Introduction ### Evolutionary History - We are evolved to run (when comparing Homo erectus to modern man) - Shoulder evolved to stabilize head when running - Longer legs, lighter lower legs and forearms to increase efficiency. - Lower body shock absorption. - Plantar arch provides spring function. - Shorter toes decrease the mechanical work involved with running at the cost of gripping capabilities. - Improved balance and coordination due to the semicircular canal in the ear. - Rapidly moving images now stabilize quicker due to eye adaptation. - Gluteus maximus muscles increased in size to stabilize the entire trunk. Large buttocks are only necessary for endurance running. - Body hair lost to aid the cooling process. - Persistence Hunting - Most quadrupeds prey are faster than humans over short distances. - Combination of running, walking and tracking to pursue prey until they are exhausted. - However, we have an unusually specialized endurance capability. ### Who is HIIT for? - Basically anyone. - Be careful in bulking phases. ## HIIT versus Continuous Training - Exercise enjoyment - Weight loss - One study demonstrates that there was no significant difference between CT and control groups. - One explanation: CT group had a greater desire to eat than the HIIT group, especially high-fat food. - When intensity increases, the total caloric expenditure increases exponentially. - Exercise duration - Improved fat burning potential - The increase in the number of and size of the existing mitochondria - Excess Post-Exercise Oxygen Consumption (EPOC), aka the _afterburn effect_. - The elevated level of oxygen consumption will last for several hours. - Energy Systems - ATP System - used for high-intensity work, less than 10 seconds - Glycogen/Lactic Acid System - from 30 seconds up to3 minutes - Aerobic System - Anaerobic threshold - Push back the anaerobic threshold - Increasing the anaerobic capacity - Beta-endorphin - "Feel good" molecule. Might be related with "runners' high" - The higher the intensity, the more beta-endorphin is synthesized - Maximal oxygen uptake / VO2 max - Athletic performance ## HIIT Implementation ### HIIT Protocols - Interval Training and HIIT - Fartlek = Swedish for "speed play", no markers or times . Ideal for beginners. - Little/Gibala protocol (beginner) - 60 seconds high-intensity (sub-maximal) - 75 seconds recovery - Repeat for 8 - 12 cycles - Total time: 18 - 27 minutes - Tabata (advanced) - 20 seconds high-intensity (maximal) - 10 seconds recovery - Repeat for 8 cycles - Total time: 4 minutes ### HIIT Intensity - Heartrate: HR monitor or Borg scale measuring rate of perceived exertion (RPE), on a scale of 1 - 10, how hard you think you're working. > [!note] Intensity is the reason HIIT works so well, not duration. - Suggested intensity of recovery has a broad range: 40-75% maximal HR. ### HIIT Duration > [!tip] Structure HIIT sessions to last a duration of 30 minutes. - 30 minutes should be enough to deplete glycogen stores. - 30 minutes exclude warm up, cool down and stretches. - Aim to progress to decrease recovery period ### HIIT Frequency - To achieve the best results, have one HIIT session every other day. - During bulking, one session of HIIT per week. i.e. HIIT maintenance period. - Recent gains of VO2 max in previously untrained individuals are completely lost after a training cessation of only four weeks! - In cutting, do it normally. ### HIIT Protocols - Creating and Recording - Create a protocol for each new mode. - Work at 100% maximal intensity until exhaustion and record the time taken. - Record the duration of the recovery period. - Repeat and record the quantity of cycles up to 30 minutes. - Progressing - Increasing the quantity of cycles (up to 30 minutes) - Decreasing the length of recovery period (say, 5 secs at a time) ### HIIT Modes - Try as many different HIIT modes as possible. - Walking - Yes, HIIT can be done with walking. Recommended for beginners and those with injuries. - This will require a hill or treadmill at steep gradient. Weights can be added. - Running - This could be dangerous on treadmill, as changing speed is cumbersome. - Get around this issue by maintaining moderate speed but using gradients. - Gradients should be used as often as possible. Weights can be involved. - The moral is: you can always make your sprints more interesting and intense. - Cycling - Outdoor cycling or stationary bike. - Cycling is ideal for HIIT as achieving high intensity is efficient. Many researches on HIIT utilize cycling. - Involves legs only. - Rowing - Utilizes the whole body, hence reaching high intensities can be easy. - Best to increasing intensity by increasing stroke rate instead of resistance. - Focus on form! Study how to row correctly. - Skipping - Stair Climbing - Stepping - Can be carried out literally anywhere - _Delayed muscular onset soreness_ (DOMS) when we perform prolonged _eccentric_ movements, i.e. when put down heavy objects. - Fatigue caused by _concentric_ exercise can last 24~48 hours, but that by _eccentric_ exercise will last for 48 hours or more. - Stretching can reduce the severity of DOMS but not the duration - Remember to alternate leading leg! - This exercise can be taken every 5 days - Swimming - Alternate stroke rate - Use backstroke for recovery - Boxing - Use the correct punching techniques to avoid injury. - Jogging for recovery - Battle Ropes - The purest upper body HIIT exercise you can do - Waves and Hammers - Kettlebells - Dynamic stretching beforehand is recommended - Clean and Press - Begin in a half squat, taking hold of the bell and with a single clean jerk, pull the weight up to the shoulder. - Pause for a beat. Then press the weight above your head. - Keep a flat back. - Full Swing - Beginning from a half squat position, swing the bell from between your legs to the arms parallel to the floor position. - Larger range can be used. - As the weight drops down, bend at the knees and hips, going back into a half squat and swing the bell between the legs. - One Arm Snatch - Figure 8 Curl - Squat and Press - Lunge and Press - Body weight - High Knees - Squat Thrusts/Burpees - Squat Jumps