Are Your Sprint Intervals HIITing You in Your ANS?

Jamie ScottPGDipNutMed PGDipSportExMed BSc BPhEd

NEW ZEALANDthatpaleoguy.com

New Zealand Ancestral Health• Public health policy being driven by

evolutionary biology• A strong and growing base of health

professionals and academics applying evolutionary medicine

• Ancestral approaches to Maori health• Synergy Health – a paleo corporate

health company ‘gamifying’ paleo workplace challenges

• Whole9 South Pacific

Convergence

FREQUENCY

INTENSITY

TIME

TYPE

High-frequency

Moderate-to-high intensity

Long-duration

Highly-specific

Conventional Endurance Training“Chronic Cardio”

FREQUENCY

INTENSITY

TIME

TYPE

Low-frequency

High-intensity

Short-duration

Multi-modal

High Intensity Training- In Theory -

FREQUENCY

INTENSITY

TIME

TYPE

High-frequency

High-intensity

Short-to-moderate duration

Multi-modal

High Intensity Training- In Practice -

Escape from Alcatraz100 burpees over partner in plank100 dumbbell snatches100 barbell squats100 box jumps100 walking lunges1000m farmers carry100 sledge hammer strikes50 partner push ups1000m row

“I’m doing two WODs per day, 6 days per week. I don’t sleep well and I am frustrated I am not losing any weight…

…What is wrong with my diet?

Mon AM: WOD PM: WODTue AM: WOD PM: SoccerWed Rest DayThu AM: WOD PM: WODFri AM: WOD PM: WODSat AM: WOD PM: SoccerSun AM: WOD

45 minutes of box jumps, air squats, and burpees.

High-frequency, high-intensity, longer-timed workouts might not be classical marathon running or endurance cycling but which are still in effect “chronic cardio”.

With ‘paleo chronic cardio’, we are seeing similar signs and symptoms of over-training, driven not by FREQUENCY + DURATION as in traditional endurance sports, but through excessive FREQUENCY + INTENSITY.

Autonomic Nervous System (ANS)

Sympathetic Nervous System

Allows the body to function under stress

– Fighting– Fleeing

Parasympathetic Nervous System

Controls more vegetative functions

– Feeding– Breeding– Flaking out

HIT

Following an acute bout of high-intensity activity markers of sympathetic nervous system activity are disturbed and remain disturbed for at least several hours post-session.

Parasympathetic nervous system reactivation is delayed following repeated high-intensity intervals.

The first signs of autonomic stress are seen once the first ventilatory threshold (VT1) is exceeded, regardless of how that threshold is exceeded…

Continuous Movement vs. Interval Training

Seiler S, Haugen O, Kuffel E. Autonomic recovery after exercise in trained athletes: intensity and duration effects. Med Sci Sports Exerc. 2007 Aug;39(8):1366-73.

- exercise needs to conclude due to exhaustion.

ANS stress starts here.

High-intensity training zone

Whilst training above VT1 achieves a strong and positive signalling effect in terms of adaptation, it also comes with greater systemic stress requiring greater recovery.

Any prolonged efforts or repeated incursions above VT1 intensity delays ANS recovery.

The relatively lengthy ANS recovery time also brings to consideration that appropriate rest should be allowed between sessions or between training and competition. Studies examining long-term recovery have found that autonomic indices […] remain depressed […] 48h after the cessation of exercise.

Stuckey MI et al. Autonomic recovery following sprint interval exercise. Scand J Med Sci Sports. 2012 Dec;22(6):756-63.

This suggests that 2 days of recovery is inadequate for complete autonomic recovery...

Training every second day would not allow for complete ANS recovery between sessions.

In such an instance, competition performance may be hindered, or for certain populations, it may further compromise their health.

Sympathetic Nervous System Over-stimulation

Digestion. Stress hormones slow the release of stomach acid and interfere with how well the stomach can empty itself. This can cause nausea, digestive problems, diarrhoea…

Metabolic. Cortisol makes you crave carbohydrates and fats, which can cause you to gain weight. Cortisol also makes you more likely to put on weight in your abdominal area…

Immune system. The stress response depresses your immune system, slowing healing and making you more likely to get colds, infections, and other inflammatory conditions…

Mental health. Being bombarded with stress hormones creates a constant state of nervousness, tension and anxiety, impatience, hyper-vigilance, ruminations…

Adaptation?

Highly-trained athletes do seem to recover from such ANS perturbations more rapidly.

But… We are currently unable to say whether this is an actual adaptation to training or an inherent characteristic of successful athletes.

- exercise needs to conclude due to exhaustion.

ANS stress starts here.

High-intensity training zone

Polarisation

Elite athletes tend to polarise their training;

• 75-90% of training volume covers low intensity training (includes strength and movement work).

• 10-25% of training volume undertaken at intensities well above VT1 (constant movement or interval-training).

High-frequency [daily] incursions into fight-or-flight mode can make the stress-related side effects of high-intensity training cumulative and can make such training just as problematic as high-frequency, lower-intensity, long-duration “chronic cardio” training.

Seiler S. et al. Autonomic recovery after exercise in trained athletes: intensity and duration effects. Med Sci Sports Exerc. 2007 Aug;39(8):1366-73.Stuckey MI et al. Autonomic recovery following sprint interval exercise. Scand J Med Sci Sports. 2012 Dec;22(6):756-63.

West, DJ. et al. The neuromuscular function, hormonal, and mood responses to a professional rugby union match. J Strength Cond Res. 2013 Mar 27

Given the 48-72h required for full ANS recovery, the prudent prescription for high-intensity training sessions for most people would be a maximum of 2-3 high-intensity [fight or flight] sessions per week, with relatively frequent deload weeks.

Seiler S. et al. Autonomic recovery after exercise in trained athletes: intensity and duration effects. Med Sci Sports Exerc. 2007 Aug;39(8):1366-73.Stuckey MI et al. Autonomic recovery following sprint interval exercise. Scand J Med Sci Sports. 2012 Dec;22(6):756-63.

West, DJ. et al. The neuromuscular function, hormonal, and mood responses to a professional rugby union match. J Strength Cond Res. 2013 Mar 27

Are Your Sprint Intervals HIITing You in Your ANS?

Jamie ScottPGDipNutMed PGDipSportExMed BSc BPhEd

NEW ZEALANDthatpaleoguy.com