Performance in varied sports is influenced not only by the exercise intensity that can be sustained by an athlete but also by the capacity of the athlete to recover from one effort to the next. In recent years, great efforts have been made by sport scientists to better understand physiological recovery processes and accelerate the recovery of exercise capacity. Various interventions have been used in isolation or in combination by athletes seeking to improve recovery from exercise, and these have included active recovery, cold water immersion, compression garments, contrast hydrotherapy, cryotherapy, hyperbaric oxygen therapy, massage, neuromuscular electrostimulation, nonsteroidal anti-inflammatory drugs, stretching, etc. Many studies have attempted to test the effectiveness of such modalities or to carry out side-by-side comparisons, obtaining, at best, mixed results (2).
Cold water immersion has not only become a popular recovery modality among athletes in recent years but seems to be scientifically supported under various conditions (4). However, cold water immersion may be somewhat more difficult to implement during competition, whereas certain other modalities may lend themselves more easily. This has forced sport scientists to investigate more practical recovery strategies.
In a recent study (1), the authors compared compression garments, neuromuscular electrostimulation, and humidification therapy with a control condition. Adding to the importance of this study was that it involved highly trained athletes during their competition season. The group of cyclists was competing at the A- or B-grade level of their respective states in Australia. Furthermore, the testing format was designed to be similar to particular track-cycling events that consist of multiple races and, therefore, has implications for other sports involving high-intensity bouts interspersed with limited recovery time.
Mean power output was assessed as an indication of the maximal amount of work they could generate in each of three 30-second bouts of cycling, using a self-selected gearing and cadence. These all-out efforts were interspersed by 30-minute recovery intervals, which included the following sequence: a cool-down from the preceding sprint; the recovery set-up; 20 minutes with one of the 4 recovery modalities; the removal of the recovery set-up; and a warm-up for the following sprint. The intervention was executed with a room temperature of 20.7°C and the athlete in a semireclined position. Although the athletes kept their training the same during the 48 hours leading up to each of the 4 trials, they were obliged to avoid strenuous exercise during the 24 hours immediately preceding each trial.
The compression garment treatment involved 250/70 denier Lycra fiber leg sleeves that provided the lower calf with a pressure gradient of 27 ± 6 mm Hg and the upper thigh with a pressure gradient of 18 ± 2 mm Hg. The neuromuscular electrostimulation trial consisted of an electrical current at the lowest frequency (15.7 ± 2.8 Hz) that could invoke a muscle twitch, applied to the vastus lateralis muscle for the first 10 minutes, to the vastus medialis for the last 10 minutes, and to the gastrocnemius for the full 20 minutes. In the humidification intervention, a humidifier delivered warm (38°C) and fully saturated air through a nasal cannula at 45 L/min. When the athletes participated in the control condition, they simply sat in the same environment without any intervention during the 20-minute period.
When experimenting with such interventions, one cannot easily dismiss the possibility of a placebo effect. However, a belief questionnaire administered at the start of this study indicated that the results were not substantially influenced by a placebo effect because only a fourth of the cyclists correctly predicted their own best intervention and none anticipated correctly their own least effective intervention (excluding the control trial).
In the control trial, relative to the first sprint, the participants experienced an average drop in power of 2.1 and 3.1% in the second and third sprints, respectively. The effectiveness of the 3 interventions was compared with this fatigue profile. The compression strategy was determined to be possibly (>50%) beneficial in improving recovery (lesser decrement in power) during both the first (1.3%) and second (1.9%) recovery intervals. The humidification strategy did not show a clear effect in the first recovery interval but did provide a likely (>75%) beneficial effect during the second recovery interval in attenuating the loss of power (0.9%). The effect of the neuromuscular electrostimulation strategy on the power decline remains unclear.
Subject ratings of perceived recovery on a scale of 6 (very poorly recovered) to 20 (fully recovered) and blood lactate concentration were monitored at 10-minute intervals throughout each recovery period. The change in the recovery rating during the second recovery interval was likely a true effect (better perceived recovery) when the neuromuscular electrostimulation condition was compared with the control condition. With no other comparison showing a clear effect, this variable could not explain the occurrences of actual enhanced recovery and further supported the lack of a placebo effect.
The decline in blood lactate concentration was shown to be possibly greater during the second recovery interval of the neuromuscular electrostimulation and humidification conditions compared with control. With no other effect among all the interventions, it was very difficult to make any substantial connections of this particular variable to the performance results. This includes any speculation about physiologic mechanisms, including a potential to increase blood flow, possibly from compression, leading to improved lactate clearance. Overall, the lack of a direct relationship between the 2 psychophysiological variables and performance suggests that sport scientists should try to measure performance per se, and not only estimate potential benefits of recovery strategies based on mechanistic variables.
This study is not only the first (excluding 1 pilot study) to show an ergogenic effect attributable to humidification as a recovery strategy but also the first to investigate this method. Therefore, this finding should be considered preliminary; this novel modality should not be implemented by athletes before additional experimental data support its use.
Although some previous evidence exists for compression garments to enhance recovery, maybe through psychological benefits and improved local blood flow, it has not been a conclusive topic (3). The aforementioned study is the first to show an ergogenic effect of compression as a recovery strategy within a protocol of repeated bouts of high-intensity cycling with recovery intervals of limited duration. Considering that no acute direct detrimental effects of compression garment use has been shown, it is advisable for athletes facing similar competition scenarios to experiment on a personal level with compression garments during recovery periods.
Obviously, the findings of this study can also be applied to training bouts of a similar format when there is concern about inadequate recovery and performance optimization in subsequent bouts is the priority.
1. Argus CK, Driller MW, Ebert TR, Martin DT, Halson SL. The effects of 4 different recovery strategies on repeat sprint-cycling performance. Int J Sports Physiol Perform 8: 542–548, 2013.
2. Barnett A. Using recovery modalities between training sessions in elite athletes: Does it help? Sports Med 36: 781–796, 2006.
3. MacRae BA, Cotter JD, Laing RM. Compression garments and exercise. Sports Med 41: 815–843, 2011.
4. Poppendieck W, Faude O, Wegmann M, Meyer T. Cooling and performance recovery of trained athletes: A meta-analytical review. Int J Sports Physiol Perform 8: 227–242, 2013.