The metabolic systems are of vital importance to any and all physical activities, from those continuous in nature (like running, swimming and cycling), to intermittent activities, (like football codes, netball, volleyball and tennis), to explosive events that involve repeated single repetitions, (like archery, shooting and pitching in baseball). In fact, metabolic conditioning is even important for athletes that manipulate secondary objects for locomotion (like race car drivers and jockeys).
Thus, with the importance of metabolic conditioning long and well established, the training platforms that facilitate improvement are well known amongst coaches, trainers and athletes alike. Unfortunately, whilst often the need for, and concept of, a specific training medium (like interval training) is understood, the application is often theoretically diluted (like the differences in active and passive recovery between interval sets).
This article will therefore attempt to "clear the air" and provide a theoretical basis for the practical application of several key metabolic training methods.
Continuous Running (Training)
Continuous running (training) involves training at a steady pace for a long continuous period and can be sub-divided into two categories, these being:
Continuous slow – running (training).
Also known as the uniform method, (Bompa 1994,p.297) long slow distance (LSD), (Powers & Howley 2001,p.410; Wilmore & Costill 1994,p.18) low intensity continuous training (Rushall & Pyke 1993, p.202) or long easy distance (Telford 1991,p.129) , and
Continuous fast – running (training).
Also known as high intensity continuous exercise (Powers & Howley 2001,p.411; Wilmore & Costill 1994,p.17; Rushall & Pyke 1993, p.203), long solid distance (Telford 1991,p.129), or up - tempo training (Ackland & Ried 1994,p.52).
Continuous Slow - Running (Training)
As the name implies, this form of training requires the maintenance of a continuous slow pace with the objective being distance rather than speed (Wilmore and Costill,1994). The exact duration of the session varies depending on the references used. Depending on athlete experience and previous training history, a minimum of 30 to 45 minutes (even up to 60 minutes) is recommended. (Dick,1997; Shield,1994; deVries and Housh,1994; Rushall and Pyke,1993).
The greatest debate comes over training intensities. In regards to maximal heart rates (MHR), Wilmore & Costill (1994,p.18) state that an intensity of around 60% to 80% should be utilised for this form of training. Powers & Howley (2001,p.410) are more precise and state 70%, however Fox, Bowers & Foss (1994,p.308) go as high as 80% to 85%. From a Karvonen or heart rate reserve (HRR) perspective, a training intensity of 70% to 75% HRR (Fox, Bowers & Foss 1994,p.308) is deemed appropriate. When determining intensities via VO2max the variations are even greater ranging from 57% VO2max (Powers & Howley 2001,p.410) to 80% VO2max, (McArdle, Katch and Katch 2001,p.489). In simple terms, Wilmore and Costill (1994,p.18) state that "Heart rates seldom get above 160 beats per minute for the young athlete and 140 beats per minute for the older athlete."
This form of low intensity training develops both aerobic ‘base’ through aerobic adaptations (like improved fat metabolism) as well as improving basic musculoskeletal conditioning. This development of the musculoskeletal system is an important step in the preparation for the more demanding speed work (Ackland & Ried,1994; Fox & Mathews 1981). It also develops the mental discipline required for longer distance events.
Continuous Fast – Running (Training)
The difference between continuous fast - running and continuous slow - running is fairly clear the pace is faster therefore the duration is shorter (Fox, Bowers & Foss,1993; Fox & Mathews,1981). Continuous fast running is considered an effective means of improving VO2 max and lactate threshold (Powers & Howley,2001), leg speed (stride frequency or stride rate), leg strength and muscular endurance (Wilmore & Costill,1994).
The training intensity should be set at around 85% to 95% MHR (Wilmore & Costill 1994,p.17; Fox, Bowers & Foss 1993,p.308), 80% to 90% VO2 max (Powers & Howley 2001,p.411) or 80% to 90% HRR (Fox, Bowers & Foss 1993, p.398).
Both forms of continuous running do have one area for concern and this comes from the continuous skeletal impact that can lead to muscle and joint injury.
Fartlek comes from the Swedish word meaning "speed play" and was developed around the 1940s (McArdle et al. 2001,p.489). It involves alternating either speed or intensity (via terrain) during a session (McArdle et al. 2001; Wilmore & Costill,1994; Shield,1994; deVries & Housh,1994; Carr,1991) and is said to have been the forerunner of interval training (Fox, Bowers & Foss 1993,p.309). By varying speeds / intensities, not only is variety given to continuous training, but both the aerobic and anaerobic systems can be developed (Fox, Bowers & Foss,1993).
Most references mention the use of undulating terrain and variety as the key aspects to a Fartlek session, with the actual proportions of fast and slow speeds left up to the participants and how they feel (McArdle et al.,2001; deVries & Housh,1994; Fox, Bowers & Foss,1993; Telford,1991). With this in mind however, Arnheim and Prentice (2002) provide a reminder that if Fartlek training is going to improve cardiorespiratory endurance, then the heart rates need to be elevated to at least 60% to 85%.
The following example shows a "planned" Fartlek session.
||Slow to moderate pace
||60 % to 70 % pace
||80 % to 90 % pace
||Slow to moderate pace
||60 % to 70 % pace
||80 % to 90 % pace
||50% to 60 % pace
||70 % to 80 % pace
||90 % to 100 % pace
Although the example is "planned" with pace indicators, the athlete still performs what they "feel" as their 80% effort.
An example of a "free style" session may look like this.
3 Light Posts
1 Light Post
6 Light Posts
2 Light Posts
The concept of interval training, introduced by Gerschler and Reindell, (Rielly, Secher, Snell, & Williams 1990,p.112) has a strong physiological background. It involves interspersed work sessions of high intensity and recovery periods (Powers & Howley, 2001; McArdle et al.,2001; Wilmore & Costill,1994; Bompa,1994; Telford,1991; Sharkey,1990).
The session is divided into work or exercise intervals and relief intervals (Powers & Howley,2001; McArdle et al.,2001). The aim of the session is to achieve near maximal to maximal efforts with Fox, Bowers and Foss (1993,p.304) recommending heart rates from 80% to 95% of heart rate maximum or a minimum of 180 beats per minute during the work intervals. Powers & Howley (2001,p.410) push a little harder and recommend 85% to 100% maximal heart rate.
By breaking the session into short intense bouts of exercise, more total work can be achieved when compared to a single maximal effort (McArdle et al.,2001; Wilmore & Costill,1994; deVries & Housh,1994). Astrand et al. (1960, as cited by deVries & Housh 1994,p.459) found that a high workload, trained via intervals for an hour, resulted in exhaustion after only nine minutes of continuous training at the same intensity.
With interval training being more scientific than the "how you feel" approach of Fartlek training, several factors need to be considered:
Rate and Distance of Work Interval
The rate and distance of interval work depends on the energy systems to be trained. Work intervals can be either long duration at low intensity, moderate duration at moderate intensity or short duration at high intensity (Fox, Bowers & Foss,1993).
There are various methods for determining work rate. One involves reaching a THR (near maximal to maximal ) while another, devised by Wilt (1968, as cited by Fox, Bowers & Foss 1993,p.304&305) involves time over distance (as shown below).
|Event & Distance
|Run 50m or
Seconds slower than fastest
|Run 100m or
From a moving start
|Run 200m or
|Run 400m or
||1 to 4
Seconds faster than:
- Time for 400m of best 1.6 km time (400m swim) or
- Time for average 400m run or 100m swim
Run 600m - 1200m or
|Swim 150m - 300m
||3 to 4
Seconds slower than
- Time for 400m of best 1.6 km time (400m swim) or
- Time for average 400m run or 100m swim
Number of Repetitions
The number of repetitions performed depends on the distance of the work intervals. A guide by Fox, Bowers and Foss (1993, p.304) is to complete between 1.5 to 2 miles (2.4 to 3.2km) through the session. Therefore shorter intervals require more repetitions whereas longer intervals require less.
The example comes from Rushall and Pyke (1993,p.208 & 209).
|Duration of Work
||5 - 30 Secs
||2 - 5 Mins
||5 - 20
||3 - 12
Duration of Relief Interval
There are two methods of determining the duration of the relief interval.
The average guide has the heart rate returning to between 120 and 140 bpms (Powers & Howley 2001,p.410; Fox, Bowers & Foss 1993,p.305; Rielly et al. 1990,p.112) or dropping 40 to 50 bpm from the training heart range (Ackland & Ried 1994,p.69) before the next interval begins.
Rest ratios supply a more mathematical approach to recovery with the duration of the relief period associated with the duration of the work interval.
(From Fox, Bowers & Foss 1993, p.305)
||1 / 1 or 1 / 1/2 ratio
||400m - 600m
||1 / 2 ratio
||up to 400m
||1 / 3 ratio
Type of Activity During Relief Interval
Several factors determine whether the relief interval is active or passive in nature.
Rest - Relief
Rest - relief is predominantly used for those training the ATP - PCR system as rest allows a greater phosphagen recovery. Likewise those training their aerobic systems who desire minimal lactic acid accumulation have a greater lactic recovery with a rest relief protocol (Fox, Bowers & Foss,1993; Fox & Mathews,1981).
Work - Relief
Lactic acid partially blocks ATP - PCR recovery. This means that by actively moving and maintaining a higher lactate level, there will be less ATP - PCR recovery thereby placing a greater reliance on the lactic system (Fox, Bowers & Foss,1993; Fox & Mathews,1981).
Race pace or tempo (Carr 1991,p.67) training has the athlete training at the pace required for an event. For example, the athlete wants to run five kilometres in 20 minutes. The pace they need to run at is 15 km/hour or four minutes a kilometre. This pace would then be the athlete’s training pace.
As this pace is usually faster than their current pace, great strain would be placed on the athlete if they where to complete the event distance. Intensity (and possible injury) can be down graded through the use of repetitions.
Due to the common use of repetitions, race pace training is associated with repetition training which Rushall and Pyke (1993,p.212) define as "Units of work completed at competition quality." Some authorities however have slightly different interpretations of repetition training.
The interpretation of repetition running given by Fox, Bowers and Foss (1993,p.309) is divided into two methods. The first involves running repetitions of half race distance at race pace or slightly faster. The second involves running three quarters the race distance at a slightly slower than race pace. The amount of repetitions completed should allow one and a half to two times the distance of the event to be completed.
These guidelines plus the recommended length of intervals, being repetitions of 1.4 km to 3.2 km would indicate that this form of training be for the shorter aerobic events up to 6.5 or so kilometres (Fox, Bowers & Foss,1993; Fox & Mathews,1981).
Another variation, given by deVries and Housh (1994,p.460), has the repetition bouts lasting only 30 to 90 seconds. The intensity is up to five seconds faster than a 400m race pace with the total distance of the repetitions equal to, or less than, eight kilometres.
Although interpretations may differ, most authorities agree that recovery is to be more complete in repetition training than interval training (Fox, Bowers and Foss,1993; Rushall and Pyke,1993; Fox & Mathews,1981). Fox, Bowers and Foss (1993,p.309) recommend "a recovery heart rate well below 120 beats per minute." A ratio comparison provided by deVries and Housh (1994,p.461) shows a 1:5 work / rest ratio.
Some of the forms of training previously mentioned rely on established guideline times; for example; three to four secs slower than time for average 400m run used by an athlete performing 600m to 1200m intervals. As the athletes improve, the timing guidelines need to re-evaluated in order to avoid the guideline times from becoming under valued. The best means of re-evaluating these times is through competition itself or time trials.
Time trials also provide progressive evaluation. As times improve, the effect of the training regime can be evaluated and adjusted. Improved times can also provide motivation and target goals.
A note by Tulloh (1994,p.47) suggests that time trials be performed when "...you are physically rested and mentally prepared." If the time trial comparisons are to be accurate diurnal variations should also be considered.
It is generally recommended that lower intensity be the forerunner to higher intensity training. This allows the development of the physiological (eg. cardio – vascular endurance) anatomical (eg. local muscle endurance) biomechanical (eg. technique) and mental (eg. discomfort tolerance) parameters required for more intense training.
This however does not mean that one form of training has greater injury concerns; after all, whether chronic in nature, due to excessive durations, or acute in nature due to a sudden increase in intensity, an injury is an injury and carries with it the sequale of the condition.
Thus, with intensity being reliant of predisposing factors and duration being inversely related to intensity, the figure below, provides an example of the relative intensity versus duration of the training modalities. Note that Time Trials and Race pace are centrally located. This reflects the need to both cover the distance of the event but furthermore to complete the distance at speed.
It should also be noted that this pyramid is indeed simplistic and does not take into account important factors like diet, flexibility, muscle conditioning etc.
There are numerous other training regimes performed by coaches or found in reference material. Most will likely be variations of the methods discussed, again with the emphasis on either endurance, speed or a combination of both.
- Ackland,J. & Reid,B. 1994. The Power to Perform. Birkenhead,Auk: Reed Publishing.
- Arnheim, D.D. & Prentice,W.E. 2002. Essentials of Athletic Training, 5th Edition, McGraw Hill, Dubuque, IA.
- Bompa,T.O. 1994. Theory and Methodology of Training. Third Edition. Dubuque,Iowa ; Kendall / Hunt Publishing Company.
- Carr,G. 1991. Fundamentals of Track and Field. Champaign,IL : Human Kinetics.
- deVries,H.A. & Housh,T.J. 1994. Physiology of Exercise 5th Edition. Madison, Wisconsin: Brown and Benchmark.
- Dick, F.W. 1997. Sports Training Principals. Third Edition. Bedford Row,Lon: A&C Black.
- Fox,E.L. & Mathews,D.K. 1981. The Physiological Basis of Physical Education and Athletics. Third Edition. Philadelphia, PA: Saunders College.
- Fox,E.L., Bowers,R.W. & Foss,M.L. 1993. The Physiological Basis for Exercise and Sport. Fifth Edition. Madison, Wisconsin: Brown and Benchmark.
- McArdle,W.D., Katch,F.I. & Katch,V.I. 2001. Exercise Physiology 5th Edition. Malvern PA : Lea & Febiger.
- Powers,S.K. & Howley,E.T. 2001. Exercise Physiology. Fourth Edition. Madison, Wisconsin: Brown and Benchmark.
- Rielly,T., Secher,N., Snell,P. & Williams,C. 1990. Physiology of Sports. London, Great Britain : St. Edmundsbury press.
- Rushall,B.S. & Pyke,F.S. 1993. Training for Sports and Fitness. Crows Nest, NSW. Macmillian Education Publishers.
- Sharkey,B.J. 1990. Physiology of Fitness. Champaign,IL : Human Kinetics.
- Shield,T. 1994. Aerobic Fitness. Fitlink magazine. June/July. Coorparoo, Bne: Fitlink. pp. 22 -24.
- Telford,R.D. 1991. Endurance training in ‘Better Coaching Advanced Coach’s Manual’ ed. F. Pyke, Belconnen, ACT: Australian Coaching Council
- Tulloh,T. 1996. Running is easy. London,GB; Collins Willow.
- Wilmore,J.H. & Costill,D.L. 1994. Physiology of Sport and Exercise. Champaign,IL : Human Kinetics.