Strength & Conditioning

UCAN Presents: Dr. Paul Laursen and the Science and Application of High-Intensity Interval Training, Part 2

In a special 3-part webinar series, Dr. Paul Laursen – researcher, endurance coach, and high performance consultant – talks about the science of high intensity interval training (HIIT), how to apply it to team sports and concurrent (strength + cardio) training programs, and the unique factors that influence the needs and goals of athletes and individuals who incorporate strength training and cardiovascular training into their programs.

This webinar is a must-listen for personal trainers, strength/team sport coaches, and individual exercisers who strive to optimize their clients’, athletes’, or personal programs. This education series aims to help fitness professionals and individuals alike maximize overall athlete and client outcomes while minimizing or eliminating over-training and the interference effect through smart and informed programming.

Watch Part 2 below and review the show notes. Click on the links to watch Part 1 and Part 3.

Text book: Science and Application of High-Intensity Interval Training: Solutions to the Programming Puzzle

Online course: Science and Application of High-Intensity Interval Training Online Course
*Course work NSCA CEU approved

Incorporating HIIT into a Concurrent Training Program

Many sports require elements of performance that may interfere with each other: strength, speed, and fatigue resistance

Endurance training and HIIT:

  • Increase oxygen delivery
  • Increase oxygen uptake at the cellular level
  • Create new mitochondria

Strength training:

  • Increases strength
  • Muscle hypertrophy
  • Power development

*These two are not compatible types of training.

The Interference effect

When these two training modalities are blended, the literature shows that the outcomes aren’t as great as if you were to independently do endurance training or strength training

  • You would see larger benefits from whichever practice you emphasize

Often in team sports and individual sports contexts, both need to be trained

  • Why does the “Interference Effect” happen?
    • Acute/neural mechanism: HIIT sessions elicit residual neuromuscular fatigue: sore muscles, the athlete feels tired. This type of fatigue can acutely compromise strength training performance, which can attenuate the strength training adaptation
    • Chronic/molecular mechanism: there might be something that attenuates muscle signaling under prolonged concurrent training

*You must pay close attention to how much residual neuromuscular fatigue is actually occurring in either a strength training session or a HIIT session

Key Points for Concurrent Strength Training Programming

  • Control/influence the schedule to limit interference to make subtle adjustments to optimize adaptation
  • Limit neuromuscular fatigue to within at least 6 hours in between sessions, sometimes 24 hours if possible
    • Can be addressed two main ways
      1. If metabolic conditioning session contains an element of neuromuscular fatigue, make sure there is a window of 6-24 hours between the subsequent strength session -OR-
      2. Choose low-neuromuscular fatigue HIIT sessions in front of or after strength training sessions

Prior to strength training, HIIT sessions performed in the 24 hours prior should be of:

  • Lower neuromuscular demands
  • Lower absolute or relative work intensities

Physiological Targets of HIIT: O2 ⦻2 NM

1. Aerobic Energy System O2: with oxygen.

The heart + lungs and their maximal ability to uptake and deliver oxygenated blood to the working muscles and brain to elicit performance

  • Time at VO2max may be cardinal marker of aerobic performance
  • Increase aerobic enzymes in mitochondria

2. Anaerobic Energy System ⦻2: without oxygen

  • Elicits a lot of lactate
  • Burning sugar
  • Deplete glycogen stores
  • High level of perceived exertion

3. Neuromuscular Energy System NM- musculoskeletal strain.

  • Injury risk
  • Residual fatigue
  • High level of perceived exertion
  • Decreased performance

*You can form a HIIT session purposefully to target any/some/all of those three physiological aspects

HIIT Precision

  • HIIT templates can provide varying degrees of emphasis on each physiological target, allowing HIIT training to be very precise
  • HIIT color coding to understand physiological target of a particular session:
    • Aerobic Energy System: green O2
    • Anaerobic Energy System: red ⦻2
    • Neuromuscular Energy System: black NM
  • Not all 3 of the systems need or should be targeted simultaneously in every single HIIT training session
    • Tailor HIIT sessions to the intended adaptations, and save other systems for another day
  • Common programming mistake: constantly taxing all 3 systems
    • Going too hard too often
      • 3 physiological targets O2, ⦻2, NM not considered

Manipulating HIIT

12 Main Variables

  1. Work bout intensity
  2. Duration of the work bout
  3. Recovery period intensity
  4. Recovery period duration
  5. Number of intervals or series duration
  6. Number of interval bout series
  7. Between-series recovery duration
  8. Between-series recovery intensity
  9. Total volume
  10. Exercise mode and ground surface for run-based HIIT
  11. Environment (heat and altitude)
  12. Athlete’s nutrition practices

Intensity and Duration of the Work Bout – Factors 1 and 2

HIIT training occurs above threshold

  • At the upper end: maximal sprinting speed or peak power output. As fast as you can move over 4 seconds or as much power as you can produce over 4 seconds

What are we hitting when we hit these different HIIT intensities?

1. Fast twitch muscle fibers

    • Powerful muscle fibers that fatigue very fast

2. Slow-twitch muscle fibers

  • Fatigue resistant, not very powerful

3. Intermediate fibers

  • The best of both worlds

*HIIT targets Intermediate and Fast Twitch fibers with the goal of making them more fatigue-resistant.

Power/Speed Time Continuum

Describes the interplay and tradeoff of exercise intensity and duration in a particular individual completing a specific movement task or exercise.

  • As intensity increases, duration decreases
  • The lower the intensity, the greater the potential duration

Recovery Intensity and Duration of Work Bout

  • If intensity of active recovery is too high, can cause further depletion and diminish performance and not allow the body to recover as fast as it could
  • If duration of active recovery intensity is too short for the given work bout, it can also limit subsequent work bout performance
  • Study: 15 seconds on, 15 seconds off HIIT session in team sports athletes
    • “Off” was active OR passive recovery
    • 15 seconds on : subjects went to exhaustion
    • Passive recovery group: subjects were able to go 2x longer than those doing active recovery
    • Active recovery even at 40% VO2 max-as in this study- simply doesn’t allow as many repeatable efforts at max intensity

*If maximal recruitment is necessary (those fast twitch muscles that HIIT tries to target) then we want to hit them repeatedly: passive recovery is more appropriate

Recovery Guidelines

If goal is speed and increasing fatigue resistance in fast twitch muscle:

  • Passive recovery
  • Longer recovery durations

If goal is maximal aerobic metabolic conditioning effect:

  • Active recovery is probably the right play
  • Aerobically conditions athlete

*Context is key for deciding recovery

WANT MORE? REVIEW PART 1 AND WATCH PART 3 TO CONTINUE LEARNING ABOUT HIIT SCIENCE.