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| Study | Type | Program overview | Time of year |
Duration (weeks) |
Frequency | Volume (duration) & intensity per session |
ST/SIT replaced or added |
ST supervised? |
Endurance training | Total training |
|---|---|---|---|---|---|---|---|---|---|---|
| Paavolainen et al. |
The strength training for I was divided into explosive (E), heavy resistance (H) and sprint (S) training | E: Jumping and specific RS exercises (low loads/high velocities). H: Squats with barbells and exercises specific for skiers S: NS |
Preparation period (autumn) | 6 | 6-9 training sessions/ week – 34% (weeks 1-3) and 42% (weeks 4-6) strength. | 15-90 min H: 70-90%1RM |
NS | NS | 1-4 h/session (66% first 3 weeks, 58% last 3 weeks) Documented (volume, frequency, exercise mode) |
6-9 times/week (divided into END-STR) |
| Hoff et al. |
Maximal strength | Pull-down sitting on a bench | Preparation period (October- December) | 9 | 3 sessions/week | I: 3x6RM (85% 1RM, with a 1-kg increase if 3 sets were completed successfully) C: General STR <60% 1RM or >20 reps |
NS | Yes (every second week by the investigators, every week by trainers) | Mainly running during the first 4 weeks, then RS for the last 5 weeks Documented (volume, intensity) |
Average weekly training volume of 8.5±0.8 and 9.2±1.2 h for I and C, respectively |
| Hoff et al. |
Maximal strength | Pull-down sitting on a bench | Pre-season (months, NS) | 8 | 3 sessions /week | 45 min/week I: 3x6RM (85% 1RM, with a 3-kg increase if 3 sets were completed successfully. 3-4 min rest between series) C: Strength endurance <85% 1RM |
NS | Training sessions were monitored only three times by the investigator, but every week by the trainers. | 9.15 h/week Documented (volume, intensity, exercise mode) |
10 h/week |
| Østerås et al. |
Maximal strength | Pull-down sitting on a bench | Autumn prior to the start of competition season | 9 | 3 sessions / week |
45 min/week I: 3x6RM (85% 1RM, with a 3-kg increase if 3 sets were completed successfully. 2-3 min rest between series) C: Strength endurance <85% 1RM |
Replaced | Training sessions monitored only three times by the trainers. | I: 12.8 h/week/ C: 10.5 h/week Documented (volume, intensity, exercise mode) |
I: 14 h/week; C: 12 h/week |
| Nilsson et al. |
Sprint-interval training | DP interval training on an ergometer with 20-s (IT20-s) or 180-s (IT180-s) intervals | Preparatory period (May to first half of June) when the subjects had recovered from the competitive season |
6 (16 sessions) |
3 sessions/week |
IT20-s: 20-s intervals with maximal power output and 120-s rest. Number of intervals increased from 11.7 to 14.7 over the training period. IT180-s: 180-s intervals with power output = 85% mean power output during 6-min performance test with 90-s rest (power increased 14% during this test to compensate for improvement in performance). Number of intervals increased from 6.0 to 7.5 over the training period. |
STR replaced by 20- or 180-s sprint intervals | All training sessions were supervised and documented by the experimenters | Pre-dominantly low-intensity aerobic training performed as RS, running with and without poles and cycling. Documented (volume, intensity, exercise mode) |
IT20-s: 8.4 h/week IT180-s: 8.1 h/week C: 8.6 h/week |
| Nesser et al. |
Circuit training (Cir) Roller board (RB) Ski-specific (SS) Weights (WT) |
Cir: Pull-ups, push-ups, chair dips and sit-ups – using body weight only. RB: Roller board with adjustable angle for modifying resistance SS: Short maximal uphill RS sprints, ski-specific (arm and abdominal) plyometrics and uphill bounding with poles. Rest intervals: 3 min. WT: Lat-pullover with press, upright row, lat pulldown, triceps pulldown, bench press and seated row. |
Summer training program | 10 | All groups 3 sessions/week |
Cir//RB/ SS: ~30 min/session; Cir: To fatigue or for 30 sec (30-s rest between exercises) RB: 3–8RM (slow movements and long rest) for strength or 10–12RM (explosive and long rest) for power. Rest intervals: 3-5 min. SS: Short maximal (rest: 3 min). WT: ~25 min/session. Load varied from 3–8RM (slow movements) to develop strength to 10–12RM (slightly higher speeds) to develop power (rest: 3-5 min). |
NS | Coaches monitored and led the training of one group each. | Cir: 4.7 h/week RB: 3.3 h/week SS: 6.6 h/week WT: 4.6 h/week Documented (volume, intensity, exercise mode) |
Cir: 6.3 h/week RB: 4.8 h/week SS: 8.2 h/week WT: 5.7 h/week |
| Mikkola et al. |
Explosive-type strength (general and sport-specific exercises) | Sport-Specific Rapid Force production (SSRF): DP RS or sprinting/bounding uphill with poles. Explosive strength (EXPLO): half squat, bench press, pullover, incline row, abdominal curl, back extension, leg press, lat pulldown, etc. Explosive training (EXPLO_A): running sprints (RS), alternative jumps (AJ), skating jumps (SJ), calf jumps (CJ). |
Autumn, during the early phase of preparation for competition | 8 | 3 sessions/week |
The explosive training sessions lasted 30-75 min with volume for upper- and lower body being approximately the same. The typical speed training session consisted of 10-15-s sprints (running or DP) with 2-3-min recovery. The strength training usually consisted of 6-10 exercises (half squat, bench press, pullover, abdominal curls, back extensions, etc.) with 2-3x6-12 sets/reps. The training was performed with low loads, but at high velocities. SSRF: 10–15x10–15 s; EXPLO: 3 x 6–10 reps; RS: 3–6x30 m, AJ 4–6x20, SJ 4–6x20, CJ 4–6x10–15 |
Replaced | NS | Endurance training typical for XC skiers, such as RS, running and Nordic walking. Most of endurance training below anaerobic threshold. Documented (volume, intensity, frequency) |
Total training volume was the same in both groups (I: 10.3±1.1 h and 10±0.5 h/week, C: 11.1±3.1 h and 11±1.0 h/week) |
| Losnegard et al. |
Maximal strength | Half squat, seated pulldown, standing DP and triceps press | During the basic preparatory period (beginning of June to end of August) | 12 | 2 sessions /week |
Training sessions approximately 45 min. Half squat, seated pulldown and triceps press: 3-4 x 5-10 reps; Standing DP: 3x10RM (Rest: 2-3 min) |
Added | Individual supervision of the three first sessions by an investigator to ensure proper technique and appropriate work load. | I: 15.2±1.1 h; C: 15.3±0.7 h Documented (volume) |
NS |
| Rønnestad et al. 2012 | Heavy Strength training | Deep squat, seated pull-down, standing DP | Beginning of the preparation period | 12 | 2 sessions /week |
3-5 sets/session 3-5RM (70-80% 1RM) Standing DP: 10RM |
Added | All athletes supervised by an investigator during all workouts for the first 2 weeks and thereafter once every week throughout the intervention. | No differences between the groups regarding the total volume of endurance training or distribution of this training within HR intensity zones. Documented (volume, intensity, frequency, exercise mode) |
Same total weekly duration (including heavy strength training) by the two groups: 12.0±0.6 h |
| Skattebo et al. |
Heavy strength training | Seated pull-down, standing DP and triceps press | Mid-September to end of November (late pre-competition period). |
10 | 2-3 sessions /week | Three sets per exercise. Each session, including warm-up, lasted ~ 40 min. 10RM-4RM Each repetition was conducted with maximal mobilization in the concentric phase (lasting approximately 1 s), followed by a slower eccentric phase (2–3 s). Rest between sets: 2–3 min. |
Added | To help ensure that the subjects lifted with proper technique and optimal load, they were encouraged to attend strength training sessions supervised by experienced coaches. |
Both groups continued their normal aerobic and endurance training. I: 11.2±1.8 h: HIT 0.5±0.2 h; MIT 0.3±0.2 h; LIT 10.3±1.6 h C: 10.6±1.3 h: HIT 0.5±0.2 h; MIT 0.3±0.1 h; LIT 9.7±1.3 h Both groups performed similar amounts of ski skating (~ 27%), classic XC skiing (~ 28%), running (~ 40%), and other types of exercise (cycling, rowing etc.; ~5%). Documented (volume, intensity, frequency, exercise mode) |
I: 13.8±2.3 h C: 12.7±1.4 h |
| Vandbakk et al. |
Sprint-interval training | Session 1: 30-s upper-body sprint-intervals (DP RS) uphill outdoor at maximal sustainable effort Session 2: RB while kneeling. |
June-November | 8 | 2 sessions /week | 6-8x30-s intervals of upper-body sprint separated by 2-3 min active rest (i.e., 15-20 min of total work duration for each session. Maximal sustainable effort (iso-effort). |
Added | NS | I: LIT 9:48±1:57 MIT: 0:25± 0:08 HIT: 0:38±0:07 SI: 0:30±0:11; C: LIT: 10:10±2:54 MIT: 0:37±0:14 HIT: 0:36±0:10 SI: 0:00±0:01 Documented (volume, intensity, frequency, exercise mode) |
I: 13:27±2:26 h; C: 13:54±3:44 h The total amount of training was individualized, i.e., not all skiers trained for exactly the same number of hours. Differences in the amount of LIT accounted for most of these individual differences. |
| Øfsteng et al. 2018 | Heavy strength training (STR) with or without vibration (STR_VIB), in addition to their ongoing endurance training. In addition to endurance training (without any additional strength training) C was allowed to perform whole-body stability and core training. |
Standing DP, seated pull-down and triceps press with or without 50-Hz vibrations of the wire in the custom-made pulldown apparatus. The daily undulating periodization of STR progressed toward fewer repetitions with higher loads. The first and last sessions each week were continued to failure, with the load adjusted in accordance with the RM principle. The second strength session each week was executed with a ~10% reduced load in comparison to the predicted RM (i.e., the sets were not continued to failure). The skiers were instructed to perform with maximal acceleration and speed during the concentric phase (lasting around 1 s), while the eccentric action was performed more slowly (i.e., lasting around 2-3 s). On days when both END and STR were performed, the skiers were encouraged to perform STR first. |
The intervention period started 5 weeks after the competitive season ended. | 8 | 3 sessions /week | 3 sets of each exercise First 3 weeks: 10, 12, and 6 repetitions during the 1st, 2nd and 3rd STR session of each week, respectively. Following 3 weeks: 8, 10, and 5 repetitions during the 1st, 2nd and 3rd session, respectively, adjusted to 6, 8 and 4 repetitions for the final 2 weeks. Inter-set rest periods of 2-3 min. |
Added | All workouts were supervised by one of the investigators. |
No significant difference in the weekly duration of END or its distribution as LIT, MIT, and HIT between the STR (13±3, 1±1,1±1 h) and C groups (10±5, 1±1, 1±0 h). No difference in the time spent running, cycling, performing DP, or other types of ski training each week (4±1, 1±1, 2±2 h, 7±2 h vs. 4±1, 1±1, 2±2.5±2 h, respectively). Documented (volume, intensity, exercise mode) |
The STR groups trained more than the C group. During the intervention, the STR groups added traditional heavy strength training with or without vibration to their ongoing endurance training. The C group continued their usual endurance training, with no additional strength training. |