Originally Posted by Dare Vodusek
What are healthy limits? I can keep my hr very close to 95% for long time, but if thats unhealthy...I rather dont.
95% is mega high. HIIT (High Intensity Interval Training) like Crossfit usually plays in the upper end of the tolerance limit, but 95% for too long isn't good for you.
The traditional method for calculating HR zones:
220 - Age = MAX HR
Max HR x 50% to 75% = "Fat Burning Zone", a cozy zone where you can maintain this comfortably for the long haul. This can be sustained almost indefinitely.
Max HR x 75% to 85% = "Cardiovascular Development Zone", a sweaty and hard breathing zone where you're really doing work. This can be sustained, but is difficult, and you'll generally see upward HR drift at the same output level (i.e. treadmill running at same speed or cycling with same resistance) over time. This can be a 10-20min workout, 30min might cause excessive CV fatigue in most athletes. This should be your target "time-averaged" HR zone during a HIIT workout.
Max HR x 85% to 90% = "Threshhold Zone", an uncomfortable zone where prolonged activity at this level without breaks (i.e. the rests in HIIT) can get hairy, exceeding this "Threshhold" doesn't benefit the athlete, and can cause negative results. This can be sustained for short bursts, but shouldn't be maintained too long. (5-10min is LONG at this level).
Max HR x 90% to 100% = "Excessive Zone", uncomfortable and dangerous area where you're not benefiting yourself any more than Zone 2 or 3, and actually running the risk of overexerting yourself, causing excessive fatigue and prolonging recovery time. It should not be used, and not be intentionally sustained for any amount of time.
The Traditional Method is ONLY based on Age and percentages, so it doesn't factor in ANY fitness attributes of the athlete.
The more "Modern Style" for calculating a specialized heart rate zone break-down, which fits more closely to "perceived effort" and adjusts more accordingly to an athlete's actual condition, rather than their age:
Max HR = 220 - Age
HR Reserve = Max HR - Resting HR
HR Reserve x (1 + 50% to 75%) = Fat Burning Zone
HR Reserve x (1 + 75 to 85%) = Cardio Development Zone
HR Reserve x (1 + 85% to 90%) = Threshold Zone
HR Reserve x (1 + 90%+) = Excessive Zone
One criticism of the Modern Method is that it pushes people with higher resting HR's to work at higher HR's than people with lower resting HR's. In that light, the numbers for the Modern Method will suggest a HIGHER limit for an unfit person with a high resting heart rate than it would for a fit person with a low resting HR.
So, for me:
Age = 30
Resting HR = 55bpm
Max HR = 190bpm
Fat Burning Zone = 95-143bpm
Cardio Zone = 143-162bpm
Threshold Zone = 162-171bpm
HR Reserve = 135bpm
Fat Burning Zone = 123-156bpm
Cardio Zone = 156-170bpm
Threshhold Zone = 170-177bpm
So take your pick which method you use. I use the Modern Method because I feel like the bottom end (50%) in the Traditional Method is WAY WAY too low for me to slip into the Fat Burning Zone. 95bpm for me is an increase of 40bpm, but it's nothing that feels like a workout, at any level. 125bpm starts to feel like a workout, and I generally never dip much below around 140 for my target for most workouts (since I'm not usually worried about fat burn). I try not to hang out over 175bpm for any amount of time.