Can One HIIT Session Per Week Be Enough? The Science Behind Smart Intensity Training

At Sussex Performance Centre, we’re big believers in training hard and training smart.
Between work, family and life commitments, many people struggle to train as often as they’d like — which raises a question we’re hearing more often:

If I only have time for one session a week, can I still make real progress?

Surprisingly, new research suggests the answer might be yes — provided that session is structured the right way.

The Science: Volume vs Frequency in HIIT

A 2024 study published in the Journal of Exercise Science & Fitness compared two groups of recreationally active adults:

• One performed 75 minutes of HIIT once per week

• The other performed the same total training volume split across three sessions

Both groups used typical HIIT intervals (4×4-minute efforts at 85–95% HRmax, separated by 3-minute active recovery periods).

👉 After 6 weeks, both groups showed similar improvements in:

• VO₂ max (aerobic fitness)

• Body composition

• Blood pressure

• Fat-free mass

In other words, one longer HIIT session produced comparable physiological benefits to three shorter ones — as long as total training volume was matched.
(Lee et al., 2024, J Ex Sci Fit)

This doesn’t mean you should only train once a week, but it highlights that intensity and total load can often matter more than frequency for maintaining or improving fitness.

Why It Works

HIIT (High-Intensity Interval Training) challenges your cardiovascular system to operate near its maximum, improving the heart’s stroke volume, mitochondrial efficiency and oxygen utilisation.

When you accumulate the same total “high-intensity minutes,” your body experiences a similar adaptive stress — even if you condense those minutes into fewer, longer sessions.

However, this only works if:

• You push into the correct intensity zones (85–95% HRmax).

• You recover fully between intervals.

• You have good baseline fitness and tolerance for longer HIIT blocks.

How We Use It at SPC

At SPC Blast, we already apply these principles — short, intense, efficient conditioning sessions designed for maximum results in minimal time.

Our programming uses formats like:

• Norwegian 4×4 protocol: 4 rounds of 4 minutes hard work, 3 minutes recovery.

• Mixed-modality HIIT: Row, SkiErg, Bike, sleds and carries — all programmed for heart-rate-based intensity.

• “Time-crunch conditioning” blocks: Full-body EMOM or AMRAP sessions lasting 35–45 minutes that hit both aerobic and anaerobic systems.

If a client can only attend once per week, we modify their approach by:

1. Increasing total session load — slightly longer working sets or additional intervals.

2. Tracking intensity — ensuring work is genuinely high-output.

3. Encouraging complementary movement — walking, mobility or light strength work on other days to maintain weekly activity.

The goal isn’t to train less, but to train efficiently when time is tight.

🏋️ Sample SPC-Style Once-a-Week HIIT Session (45 minutes)

Warm-Up (10 min):

• 5 min cardio (Ski Erg / Row / Bike)

• Dynamic mobility and activation

• 2×30 sec progressive intervals

Main Block:

• 4×4 min hard efforts @ 85–95% HRmax (e.g. Row Erg or Echo Bike)

• 3 min light recovery between rounds

Finisher (Optional):

• 5× (30 sec sled push + 30 sec rest)

Cool-down (5 min):

• Easy cardio + breathing work

You’ve now completed roughly 75 minutes’ worth of “HIIT load” condensed into one session.

Pros and Cons

✅ Pros:

• Time-efficient for busy schedules

• Maintains aerobic and metabolic fitness

• Enhances discipline for high effort

⚠️ Cons:

• Higher fatigue in a single session

• Harder to recover if intensity is misjudged

• Doesn’t replace strength or skill-based training

SPC Coach’s Tip

For many of our SPC Blast members, one elite-effort session a week beats three half-hearted ones. What matters most is showing up, pushing with intent, and recovering properly.

If you’re short on time but still want to feel fitter, faster and more resilient, join our next SPC Blast. It is a 30 minute HIIT class that runs every Saturday 9;15am – 9:45am.
Sessions are designed to deliver science-backed conditioning that works — even when life gets busy.

👉 Enquire or Book Here via our Link in Bio

🔗 References

1. Lee, J. et al. (2024). Effect of Once-Versus Thrice-Weekly Volume-Matched High-Intensity Interval Training on Body Composition and Cardiometabolic Health. Journal of Exercise Science & Fitness, 22(2), 101–109. ScienceDirect link

2. Helgerud, J. et al. (2007). Aerobic High-Intensity Intervals Improve VO₂ max More Than Moderate Training. Medicine & Science in Sports & Exercise, 39(4), 665-671.

3. Tjønna, A. E. et al. (2008). Aerobic Interval Training vs. Continuous Moderate Exercise in Metabolic Syndrome. Circulation, 118(4), 346-354.