Training intensity distribution

https://pmc.ncbi.nlm.nih.gov/articles/PMC4621419/

KEY CONCEPT 1. Training-intensity distribution.

The intensity of exercise and its distribution over time is one essential variable for prescribing the training stimulus. The training intensity is typically divided into zones on the basis of parameters such as heart rate, blood levels of lactate, gas exchange, power output or velocity, and/or perceived exertion.

KEY CONCEPT 2. High intensity training.

High-intensity or “zone-3” training (e.g., >4 mmol lactate/L blood, >90% maximal heart rate) involves mainly interval training, intermittent intervals, or burst-training (short, high-intensity sprints).

KEY CONCEPT 3. High volume low intensity training.

Low-intensity training (e.g., below the first ventilatory threshold or at stable lactate concentrations < 2 mM) of longer duration, also referred to as long slow distance training or “zone-1” training.

KEY CONCEPT 5. Polarized training.

The polarized training consists of significant proportions of both high- and low-intensity training and only a small proportion of threshold training. The distribution between low and high intensity training is often quantified as 80:20%, or 75–80% with low intensity, 5% threshold intensity, and 15–20% as high intensity training.

KEY CONCEPT 6. Pyramidal training intensity distribution.

With the pyramidal distribution, most training is at low intensity, with decreasing proportions of threshold and high-intensity training.

KEY CONCEPT 7. Key components of endurance performance.

In connection with many endurance sports five key parameters are utilized for comparison of performance: (1) peak oxygen uptake; (2) velocity or power output at the lactate threshold; (3) work economy; (4) peak running velocity or peak power output, and (5) time to exhaustion.

DATA

Exercise-intensity distribution during the preparation period

From 1990 to 2014, the TID of elite, nationally ranked to world-class athletes who were training in their preparation phase were reported. These athletes competed in rowing , running, cycling, and cross-country skiing. Findings indicate that elite endurance athletes spend a high percentage of their Taining Intensity Distribution in a pyramid shape, that is, great portions of High volume low intensity training with 84–95% in zone 1, 2, 11% in zone 2, and 2–9% in zone 3.

Exercise-intensity distribution before the competition phase

Depending on the competition calendar the Training Intensity Distribution during the pre-competition phase, may vary between endurance disciplines. The TID* during pre-competition was analyzed in rowing , running, cycling, junior cross-country skiers, and senior elite cross-country skiers and biathletes.

In elite rowers the Training Intensity Distribution during the pre-competition is inconclusive: in two studies the successful rowers decreased the proportion of High Volume Low Intensity Training to 70–77% with increasing proportions of zone 2 up to 15–22%, and zone 3 to 5.8–6%.

In contrast, two studies reported very high proportions of HVLIT (90–95%) during the pre-competition phase. In professional cyclists and top-class runners engaged in pre-competition training, similar proportions of HVLIT were reported (78%). The distribution of zones 2 and 3 were however, polarized (4 and 18%) in the runners and pyramidal (17 and 5%) in the cyclists.

Comparable with the findings in several studies with rowers, elite cross-country skiers and biathletes focus on HVLIT during the pre-competition phase (~91.8% zone 1–2 and 8.2% zone 3–5).

However, the competitive junior cross-country skiers in the study of Seiler and Kjerland reported a polarized TID of 75, 5–10, and 15–20% in zones 1, 2, and 3, respectively, over a 32 days period during the pre-competition phase (End October, November).

Summarized, elite athletes in rowing and cycling reported pyramidal TID with HVLIT ranging from 78% in cycling up to 90–95% in some rowers, cross-country skiers, and biathletes. Billat et al. and Seiler and Kjerland reported a polarized TID with a greater proportion of zone 1 (75–78%) and zone 3 (15–20%) compared to zone 2 (4–10%).

Exercise-intensity distribution during the competition phase

Documentation of the TID during the competition period is rare since technical equipment may not be applied during competition, the TID largely depends on the amount and type of competitions (e.g., single races vs. stage races), and the strategies for tapering for competitions vary widely across sports. Lucia et al. reported a pyramidal TID (70/23/7%) during the Tour de France based on the “HR time in zone” method over 22 competition days. The exercise intensity was particularly high during the time trials and high mountain stages. Also Lucia et al. reported that elite cyclists performed approximately 810 km·wk⁻¹ (May) with a TID of 77/15/8%, while elite cross-country skiers and biathletes showed a higher proportion of HVLIT compared with THR and HIT (~87.5% zone 1–2 vs. ~12.5% zone 3–5) when compared with the cyclists.

Exercise-intensity distribution based on seasonal analysis (up to 1 year)

The TID covering a period of several months up to 1 year was reported in cycling, swimming, running, and cross-country skiing. Athletes from the different studies incorporated a high amount of HVLIT (70–94%), with variations in the amount of THR (4–22%) and HIT (2–11%), either as pyramidal or polarized TID.

In elite cyclists a trend from a nearly complete HVLIT (preparation period) toward pyramidal TID (pre-competition, competition period) can be observed. In a 7 month longitudinal study, professional cyclists increased both the training volume (267 vs. 713 vs. 810 km·wk⁻¹, 15,000 total km) and intensity from active rest (88/11/2%) to pre-competition (78/17/5%) and competition phases (77/15/8%). Comparable findings were reported in U23 elite cyclists with a 78/20/2% TID during the winter (“volume mesocycle”) and 70/22/8% during the spring (“intensity mesocycle”). The recordings (29,000–35,000 km·yr⁻¹) for the 4000 m team pursuit cycling world record in the year 2000 (excluding stage racing and track competitions), showed a main training focus on HVLIT with 94% < LT, 4% around LT, and 2% > LT.

Comparable with the TID in the cycling studies during the pre-competition phase, regional- and national-class Spanish runners (4–5 h·wk⁻¹) demonstrated a pyramidal TID of 71 (< VT₁), 21 (VT₁–VT₂), and 8% (>VT₂) over a 6 month period. The TID of national and international-level swimmers revealed a pyramidal TID (although the athletes spent almost the same time in zone 2 and 3) over an entire season (77/12/11%). The Norwegian elite cross-country skiers and biathletes analyzed during the year leading to their most successful career competition (1985–2011) spent 91% of their training time in zones 1–2 and 9% in zones 3–5 or 77 vs. 23% when applying the session goal approach. The monthly frequency of HIT sessions and “zone 5” sessions increased from the general to the specific preparation period and remained unchanged within the competition period. From the end of the general preparation to the peaking phase, the amount of HVLIT decreased by 21%, and HIT—especially zone 5—increased by 40%. Therefore, the TID changed from an emphasis on HVLIT during preparation, toward a pyramidal TID during pre-competition, and a polarized TID during the competition phase.

In summary, most retrospective studies on well-trained to elite endurance athletes report a pyramidal TID, with a large proportion of HVLIT. Polarized TID has been proven to be an effective strategy for some elite athletes during certain phases of the season. However, experimental studies lasting 6 weeks to 5 months demonstrate superior responses to polarized TID, especially when compared with TID that emphasizes THR or HVLIT. As pointed out, the combination of HVLIT with HIT may improve endurance performance with potentially less autonomic and hormonal stress and boredom. The reasons for the non-uniform TID among endurance disciplines may arise from differences in methodology in retrospective analyses and/or high inter-individual variation in the training response. Furthermore, the long-term effects of different forms of TID (e.g., inverse pyramidal or inverse polarized or exclusive HIT) with different patterns of periodization on well-trained to elite endurance athletes, have yet to be characterized. Consequently, an “optimal” TID cannot be identified, and future prospective randomized investigations conducted over extended time-periods will have to be designed to address this question.