South African Ironman Triathlon Research Articles

Injury and illness profiles during the 2014 South African Ironman triathlon


 Background: There is a need for ongoing scrutiny of injury and illness profiles of ultra-distance athletes. This study aimed to record the medical history, illness and injuries of athletes receiving medical attention during the 2014 Ironman South Africa (IMSA) triathlon, and to investigate the temporal presentation of medical encounters. 
 Methods: This was a retrospective, cross-sectional study. All athletes who required medical attention at the main medical tent and all of the medical posts or mobile units along the route were included in this study A total of 2 331 athletes started the race. Data included age, gender, time and stage of the race when medical attention was required, pre-race medical history and medication use, illness and injuries treated, special investigations performed, and weather conditions. 
 Results: Overall, 179 athletes (7.7%) required medical attention. The incidence of medical encounters was 7.8%. A significantly higher percentage of younger participants encountered medical problems (P = 0.04). Most patient encounters (80.1%) occurred after the race. The median duration of treatment was 26 minutes. Medication was used by 35.1% of patients during the race. The most common medical encounters were exertion-related (71.2%), gastro-intestinal (16.4%), dermatological (11.9%), musculoskeletal (9.6%) and cardiorespiratory conditions (2.4%). 
 Conclusion: Medical encounters occurred more frequently in later stages of the race. Most medical conditions were exertion-related. Potential higher risk may be associated with medication use, recent illness, and in younger participants. Temporal stacking of medical personnel, planning of resources according to expected conditions, preventative measures for high-risk behaviour, and on-going data collection with comparable methodology are recommended.

A variant within the AQP1 3ʹ-untranslated region is associated with running performance, but not weight changes, during an Ironman Triathlon

The objective of this study was to test the association of the rs1049305 (G > C) variant within the 3ʹ-untranslated region of the aquaporin 1 gene, AQP1, with changes in body weight, post-race serum sodium concentration and performance in Ironman triathletes. Five hundred and four male Ironman triathletes were genotyped for the rs1049305 variant within the AQP1 gene. Change in pre- and post-race body weight was calculated for 470 triathletes and used as a proxy for changes in body fluid during the race, as well as to divide triathletes into biologically relevant weight-loss groups (0–3%, 3–5% and >5%). There were no rs1049305 genotype effects on post-race serum sodium concentrations (P = 0.647), pre-race weight (P = 0.610) nor relative weight change during the Ironman Triathlons (P = 0.705). In addition, there were no significant differences in genotype (P = 0.640) nor allele (P = 0.643) distributions between the weight loss groups. However, triathletes who carry a C-allele were found to complete the 42.2-km run stage faster (mean 286, s = 49 min) than triathletes with a GG genotype (mean 296, s = 47 min; P = 0.032). The AQP1 rs1049305 variant is associated with running performance, but not relative body weight change, during the 2000, 2001 and 2006 South African Ironman Triathlons.

Collagen gene interactions and endurance running performance

Background. Although variants within genes that encode protein components of several biological systems have been associated with athletic performance, limited studies have investigated the collagen genes that encode the structural components of connective tissues.Objective. To investigate the association of variants within collagen genes with endurance performance in South African (SA) Ironman triathletes.Methods. A total of 661 white, male participants were recruited from four SA Ironman triathlon events for this genetic case-control association study. All participants were genotyped for COL3A1 rs1800255 (G/A) and COL12A1 rs970547 (A/G).Results. No independent associations were identified between COL3A1 rs1800255 and COL12A1 rs970547 and overall finishing time or time to complete any of the individual components (3.8 km swim, 180 km bike or 42.2 km run) of the 226 km event. The major G+A-inferred pseudo-haplotype, constructed from COL3A1 rs1800255 and COL12A1 rs970547, was, however, significantly (p=0.010 and p=0.027) overrepresented in the fast run tertile (58.7%) compared with the middle (53.5%) and slow (49.5%) run tertiles, respectively. The major G+T+A-inferred pseudo-haplotype, constructed from COL3A1 rs1800255, COL5A1 rs12722 (T/C) and COL12A1 rs970547, was again significantly (p=0.022) over-represented in the fast run tertile (35.2%) compared with the slow run tertile (28.9%).Conclusion. Our main novel finding was that the COL3A1 rs1800255 and COL12A1 rs970547 variants interacted to modulate endurance running performance in the four SA Ironman triathlons investigated. In addition, the interaction between these variants and COL5A1 rs12722 appeared to modulate endurance running performance.

ACE Activity and Endurance Performance during the South African Ironman Triathlons

The insertion allele of the angiotensin-converting enzyme (ACE) gene has been associated with endurance performance. Since a large portion of the variance seen in circulatory ACE levels is unaccounted for by the insertion/deletion polymorphism it is likely that the ACE phenotype would serve as a more informative marker in assessing elite endurance performance. The aim of this study was to correlate plasma ACE activity with performance of a homogenous population of South African-born Caucasian male triathletes. Plasma ACE activity was determined in 145 triathletes, representing the fastest and slowest subgroups who completed either the 2000 or 2001 South African Ironman Triathlon. There was a trend for lower mean plasma ACE activity in the fastest (28.85±8.60 mU/ml) when compared to the slowest finisher subgroup (31.65±8.75 mU/ml, P=0.055). There was a significant positive correlation between plasma ACE activity and overall finishing time within the participants who completed the event in under 15 h (r=0.192, P=0.029). There was also a positive correlation with cycle (r=0.195, P=0.034) and run (r=0.184, P=0.040) stages but not the swim stage (r=0.084, P=0.353). In conclusion, this is the first study to report a relationship between plasma ACE activity and endurance performance in humans.

AVPR2 Gene and Weight Changes During Triathlons

The arginine vasopressin receptor 2 (AVPR2) plays an important antidiuretic role in regulating water balance to maintain osmotic equilibrium. The aim of this study was to determine if there were any associations between single nucleotide polymorphisms (SNPs), within the AVPR2 gene, and changes in serum sodium concentrations and/or body weight (BW) in Ironman triathletes. Caucasian male triathletes who completed either the 2000, 2001 or 2006 South African Ironman Triathlons were genotyped (n=570) for at least one SNP. Pre- and post-race serum [Na+] (pre n=514; post n=423) and BWs (pre n=556; post n=552) were measured. Triathletes were divided into 3 groups according to their relative BW loss during the triathlon (BW loss of 0-3, 3-5 and >5%). There was a significant linear trend (p=0.010, x2=6.7) for the distribution of minor haplotypes GCT, GTC and GCC across the 3 BW loss groups. The >5% group had the highest percentage (4.7%) of triathletes with minor haplotypes followed by the 3-5% (3.6%) and 3-0% (0%) groups. In conclusion, the minor haplotype constructs of AVPR2 SNPs were associated with larger BW losses during the Ironman Triathlons. This finding supports a possible genetic contribution to BW loss during endurance exercise events acting through the argine vasopression system.

COL6A1Gene and Ironman Triathlon Performance

Mutations in the type VI collagen gene ( COL6A1) cause myopathy and muscle weakness. In addition, COL6A1 knockout mice were shown to have impaired running performance and reduced muscle strength. The COL6A1 rs35796750 polymorphism (IVS32-29 T/C) has been associated with complex phenotypes. The aim of this study was therefore to determine if this polymorphism is associated with performance during the 226 km Ironman triathlon. Participants (n=661) were recruited during 4 South African Ironman triathlons. Finishing times for the 3.8 km swim, 180 km bike, 42.2 km run, and overall race were provided by the race organisers. All participants were genotyped for the COL6A1 rs35796750 polymorphism. Participants with the COL6A1 TT genotype were significantly faster during the bike (p=0.014) and overall race (p=0.030). When participants were grouped into fast, middle and slow bike finishing time tertiles, there was a significant linear trend for the TT genotype (Fast: TT=35.7%; Middle: TT=29.0%; Slow: TT=23.8%; p=0.008). No significant genotype frequency differences were observed for the swim or run of the triathlon. In conclusion, the COL6A1 gene is therefore a potential marker for endurance cycling performance. These effects may be mediated through changes to the composition of type VI collagen containing tissues, such as muscle and tendon.

The COL5A1 Gene

Running economy, a key component of endurance ability, has been shown to be associated with flexibility. Increased stiffness (inflexibility) may improve running economy and therefore endurance running ability. The COL5A1 gene, which encodes the α1-chain of type V collagen, was found to associate with measures of flexibility. Type V collagen is a quantitatively minor fibrillar collagen, which is believed to regulate fibrillogenesis within tendons and other connective tissue. The aim of this study was therefore to determine whether the COL5A1 gene is associated with endurance performance. Three hundred thirteen Caucasian male participants who completed either the 2006 or the 2007 226-km South African Ironman triathlon (3.8-km swim, 180-km bike, and 42.2-km run) participated in this study. All participants were genotyped for the COL5A1 BstUI restriction fragment length polymorphism (RFLP). The COL5A1 BstUI RFLP was significantly associated with time to complete the running component of the triathlon. Participants with a TT genotype completed the running component of the race significantly faster than individuals with a CC genotype (P = 0.019; mean ± SD: TT = 294.2 ± 52.1 min, CC = 307.4 ± 48.6 min). In addition, there was a significant linear trend (P = 0.020) in the CC genotype distribution when the run times were divided into the fastest (13%), middle (17%), and slowest (25%) tertiles. There were no significant genotype differences for time to complete the swim, the bike, or the overall race. COL5A1 BstUI RFLP, body mass index, age, and 15 wk of running training history predicted 30% of the variance in running performance. This is the first study to identify the COL5A1 BstUI RFLP as a marker for endurance running performance. Further studies are required to replicate these findings.

The interleukin-6, serotonin transporter, and monoamine oxidase A genes and endurance performance during the South African Ironman Triathlon

Previous studies have identified an association of genetic variants believed to alter physiological and biochemical processes locally within the skeletal muscle and therefore performance in the Ironman triathlon. There is growing evidence that the serotonergic system and circulating interleukin (IL)-6 levels are also involved in mediating endurance capacity. Investigators have demonstrated that recombinant human IL-6 administration and serotonergic neurotransmission manipulation, with 5-hydroxytryptamine transporter (5-HTT) and monoamine oxidase A (MAO-A) inhibitors, prior to exercise, can alter running performance, consistent with a central governor hypothesis. The aim of this study was to investigate possible associations of functional polymorphisms within the IL-6, 5-HTT, and MAO-A genes with endurance performance of Ironman triathletes. Four hundred sixty-eight male Caucasian triathletes who completed the 2000 and (or) 2001 South African Ironman Triathlon and 200 healthy Caucasian male controls were genotyped for the -174 IL-6 G/C, 5-HTT 40 base pair (bp) insertion-deletion and 30 bp variable number of tandem repeats (VNTR) MAO-A gene polymorphisms. There were no significant differences in the relative genotype distributions within the IL-6 (p = 0.636), 5-HTT (p = 0.659), and MOA-A (p = 0.227) polymorphisms when the fastest-fnishing, middle-finishing, and slowest-finishing triathletes, as well as the control groups, were compared. There were no direct associations between the IL-6 -174 G/C, 5-HTT 44 bp insertion-deletion, and MAO-A 30 bp VNTR gene polymorphisms and endurance performance in the 2000 and (or) 2001 South African Ironman Triathlons. The neurogenetic basis of the central governor requires further investigation.

No Association of the ACTN3 Gene R577X Polymorphism with Endurance Performance in Ironman Triathlons

Alpha-actinins are major structural components of the Z-discs in skeletal muscle. Alpha-actinin 3 is encoded by the ACTN3 gene and is expressed only in type II muscle fibres. Homozygosity for the nonsense mutation, 577X, within ACTN3 results in deficiency of alpha-actinin-3 but does not result in an abnormal muscular phenotype. Previous research has found an association of the 577R allele with sprinting and/or power performance. It has also been suggested that the 577X allele may confer an advantage during endurance events. Four hundred and fifty seven Caucasian male triathletes who completed either the 2000 and/or 2001 226 km South African Ironman Triathlons, and 143 Caucasian controls, were genotyped for the R577X mutation within the ACTN3 gene. There were no significant differences in either the genotype (P = 0.486) or allele (P = 0.375) frequencies within the fastest, middle of the field or slowest Caucasian male finishers and the control population. In conclusion, the R577X polymorphism within the ACTN3 gene was not associated with ultra-endurance performance in the 2000 and 2001 South African Ironman Triathlons.

Maintenance of Plasma Volume and Serum Sodium Concentration Despite Body Weight Loss in Ironman Triathletes

To examine the relationship between body weight, plasma volume, and serum sodium concentration ([Na]) during prolonged endurance exercise. Observational field study. 2000 South African Ironman Triathlon. 181 male triathletes competing in an Ironman triathlon. Body weight, plasma volume, and serum ([Na]) change from pre- to postrace. Significant body weight loss occurred (-4.9 +/- 1.7%; P < 0.0001), while both plasma volume (1.0 +/- 11.2%; P = 0.4: NS) and serum [Na] (0.6 +/- 2.4%; P < 0.001) increased from pre- to postrace. Blood volume (-0.6 +/- 6.6%) and red cell volume (-2.6 +/- 5.5%; P < 0.001) decreased in conjunction with the body weight loss. There was a strong correlation between blood and plasma volume change, both as a percentage, and absolute change in fluid volume (r = 0.9; P < 0.001). Body weight change was positively correlated with plasma volume change (r = -0.4; P < 0.001), but inversely correlated with serum [Na] change (r = -0.4; P < 0.001). Plasma volume change was not significantly correlated with serum [Na] change (r = 0.0; NS). Serum [Na] change was inversely correlated with both percentage of red cell volume change (r = -0.2; P < 0.05) and percentage body weight change (r = -0.4; P < 0.001). Plasma volume and serum [Na] were maintained in male Ironman triathletes, despite significant (5%) body weight loss during the course of the race. Body weight was not an accurate "absolute" surrogate of fluid balance homeostasis during prolonged endurance exercise. Clinicians should be warned against viewing these three regulatory parameters as interchangeable during an Ironman triathlon.

Dipsogenic genes associated with weight changes during Ironman Triathlons

Thirst is regulated by a complex interaction of signalling pathways within the central nervous system, including components of the renin-angiotensin and kalikrein kinin systems, as well as the serotonergic pathways. The aim of this study was to determine whether there were any associations between polymorphisms within the ACE, BDKRB2, NOS3 and/or 5-HTT genes with weight changes during the 2000 and 2001 226 km South African Ironman Triathlons. Pre- and post-race serum [Na(+)] and body weights, as well as genotype data, were collected from 428 (61.1%) Caucasian male triathletes who were divided into three groups according to their relative weight loss during the triathlon (0-3, 3-5 and >5%). There was a significant linear trend for the distribution of both the BDKRB2 +9/+9 genotype and the 5-HTT SS genotype between the three weight loss groups, with the >5% group having the highest percentage of athletes with the +9/+9 genotype (chi(2)=5.3, P=0.021) and the highest percentage of athletes with the SS genotype (chi(2)=5.8, P=0.016). Likewise, the >5% group had the highest percentage of athletes with the combined SS 5-HTT and/or +9/+9 BDKRB2 genotypes (chi(2)=7.4, P=0.007). In conclusion, the functional SS genotype of the serotonin transporter-linked polymorphic region (5-HTTLPR) within the 5-HTT gene and the functional +9/+9 genotype of the BDKBR2 gene were associated with larger weight losses during the Ironman Triathlons. These findings suggest the involvement of the serotonergic pathways in the control of thirst and drinking behaviour and provide further evidence for the dipsogenic effect of circulating bradykinin.

The bradykinin β2 receptor (BDKRB2) and endothelial nitric oxide synthase 3 (NOS3) genes and endurance performance during Ironman Triathlons

We have previously shown that the insertion allele of the angiotensin-converting enzyme (ACE) gene was over-represented in the fastest South-African-born finishers of the South African Ironman Triathlons. As ACE is a component of the skeletal muscle kallikrein-kinin system (KKS), the aim of this study is to determine if there are any further associations between polymorphisms within the BDKRB2 and NOS3 genes, which encode for the KKS components, bradykinin beta(2) receptor and nitric oxide synthase, respectively, and ultra-endurance performance during the Ironman Triathlons. Four-hundred and forty-three male Caucasian triathletes who completed the 2000 and/or 2001 South African Ironman Triathlons and 203 healthy Caucasian male control subjects were genotyped for the functional -9/+9 polymorphism within exon 1 of the BDKRB2 gene and the G894T NOS3 gene polymorphisms. The BDKRB2 -9/-9 genotype occurred at a significantly higher frequency when the triathlete group (27.0%) was compared with the control group (19.3%, P=0.035). When divided into tertiles, there was also a significant linear trend for the NOS3 GG genotype distribution among the fastest (35.0%), middle (40.4%) and slowest (46.9%) finishers (P=0.039). The overall finishing times of the triathletes with an NOS3 GG genotype together with a BDKRB2 +9 allele were significantly slower than those with other genotype combinations (P=0.001). The NOS3/BDKRB2 genotype (beta=-0.150, B=-31.48, P=0.002), together with body mass index and age, accounted for 14.6% of the variance in the overall race time for the triathlon. In conclusion, both the NOS3 and BDKRB2 genes are associated with the actual performance during the Ironman Triathlons.

Growth hormone 1 (GH1) gene and performance and post-race rectal temperature during the South African Ironman triathlon

Background: Some studies have suggested that the insertion allele of the ACE gene is associated with endurance performance, including the Ironman triathlon. It is possible that this association is due...

Serum Electrolytes in Ironman Triathletes with Exercise-Associated Muscle Cramping

To compare serum electrolyte concentrations of cramping and control Ironman triathletes. Triathletes suffering from acute exercise-associated muscle cramping (EAMC) after the 2000 South African Ironman Triathlon formed the cramping group (CR, N = 11). Non-cramping triathletes matched for race finishing time and body mass formed the control group (CON, N = 9). All subjects were weighed at race start and immediately post-race. Blood samples were drawn from both groups during recovery for the analysis of serum magnesium, glucose, sodium, potassium and chloride concentrations. Hemoglobin concentration and hematocrit were also measured. Surface electromyography (EMG) (mV) was recorded from a non-cramping control muscle (triceps) and the most severely cramping lower limb muscle of the CR group. EMG was recorded at the beginning of every minute for a 10-min period during recovery. There were no significant differences between the groups for body mass or percent body mass loss during the race. Post-race sodium concentration was significantly lower (P = 0.01) in the CR group than the CON group (140 +/- 2 vs 143 +/- 3 mmol.L) but was within the normal clinical range of post-race serum sodium concentrations. There were no significant differences between the two groups for post-race serum electrolytes, glucose, hemoglobin concentrations or hematocrit. Surface EMG (mV) was significantly higher (P < 0.05) in the cramping muscles than the control muscle of the CR group at 0, 3, 4, and 5 min of the 10-min recording period. Acute EAMC in ironman triathletes is not associated with a greater percent body mass loss or clinically significant differences in serum electrolyte concentrations. The increased EMG activity of cramping muscles may reflect increased neuromuscular activity.

The Epidemiology Of Exercise Associated Muscle Cramps (EAMC) In Ironman Triathletes

Despite anecdotal reports of a high prevalence of EAMC amongst triathletes, the epidemiology, including its associated factors, has not been well documented in these athletes. PURPOSE To investigate the prevalence of Exercise Associated Muscle Cramping (EAMC) in a group of Ironman triathletes. METHODS All 799 prospective participants of the South African Ironman Triathlon were sent a questionnaire to complete and return at registration (95.1% response rate). 68.5% of triathletes who responded to a section of the questionnaire detailing their cramping history reported a past history of EAMC and formed the ‘cramp-history’ (CH, n = 289) group. The remaining 31.5% reported no previous history of EAMC and formed the ‘non-cramping’ group (NC, n = 133). RESULTS A significantly greater number (p < 0.01) of the CH group reported cramping during running (37.1%) compared with swimming (28.9%) and cycling (15.6%), and during racing (46.1%) compared with training (18.8%). The majority of the CH group (56.5%) reported cramping in the final quarter of a race. The majority of the CH group rated their cramps as mild (77.5%), 17.4% as moderate and 3.6% as severe. 38.5% of the severe crampers had a family history of EAMC. The majority (58.4%) of the CH group associated subjective muscle fatigue with EAMC, although electrolyte imbalances (42.9%) and dehydration (42.6%) were also perceived to be associated with cramps. CONCLUSIONS There is a high prevalence of cramping history amongst Ironman triathletes that is often associated with running, racing and subjective muscle fatigue and occurs mostly in the last quarter of a race. A positive family history of cramping is associated with severe episodes of EAMC in some triathletes.

The Epidemiology Of Exercise Associated Muscle Cramps (EAMC) In Ironman Triathletes

Despite anecdotal reports of a high prevalence of EAMC amongst triathletes, the epidemiology, including its associated factors, has not been well documented in these athletes. PURPOSE To investigate the prevalence of Exercise Associated Muscle Cramping (EAMC) in a group of Ironman triathletes. METHODS All 799 prospective participants of the South African Ironman Triathlon were sent a questionnaire to complete and return at registration (95.1% response rate). 68.5% of triathletes who responded to a section of the questionnaire detailing their cramping history reported a past history of EAMC and formed the ‘cramp-history’ (CH, n = 289) group. The remaining 31.5% reported no previous history of EAMC and formed the ‘non-cramping’ group (NC, n = 133). RESULTS A significantly greater number (p < 0.01) of the CH group reported cramping during running (37.1%) compared with swimming (28.9%) and cycling (15.6%), and during racing (46.1%) compared with training (18.8%). The majority of the CH group (56.5%) reported cramping in the final quarter of a race. The majority of the CH group rated their cramps as mild (77.5%), 17.4% as moderate and 3.6% as severe. 38.5% of the severe crampers had a family history of EAMC. The majority (58.4%) of the CH group associated subjective muscle fatigue with EAMC, although electrolyte imbalances (42.9%) and dehydration (42.6%) were also perceived to be associated with cramps. CONCLUSIONS There is a high prevalence of cramping history amongst Ironman triathletes that is often associated with running, racing and subjective muscle fatigue and occurs mostly in the last quarter of a race. A positive family history of cramping is associated with severe episodes of EAMC in some triathletes.

Weight changes, medical complications, and performance during an Ironman triathlon

Background: Subjects exercising without fluid ingestion in desert heat terminated exercise when the total loss in body weight exceeded 7%. It is not known if athletes competing in cooler conditions...

The ACE gene and endurance performance during the South African Ironman Triathlons.

Several studies have suggested that the insertion (I) variant rather than the deletion (D) variant of the human angiotensin-converting enzyme (ACE) gene is associated with elite endurance performance. The aim of this study was to determine whether the ID polymorphism is associated with the performance of the fastest finishers of the South African Ironman Triathlons. A total of 447 Caucasian male triathletes of a variety of nationalities and athletic ability who completed either the 2000 or 2001 South African Ironman Triathlons and 199 Caucasian male control subjects were genotyped for the ACE ID polymorphism. There was a significantly higher frequency of the I allele in the fastest 100 South African-born finishers (103 I, 51.5% and 97 D, 48.5%) compared with the 166 South African-born control subjects (140 I, 42.2% and 192 D, 57.8%) (P = 0.036). There was also a significant linear trend for the allele distribution among the fastest 100 finishers (I allele = 51.5%), slowest 100 finishers (I allele = 47.5%), and control (I allele = 42.2%) South African-born subjects (P = 0.033). There was, however, no significant difference in the ACE genotype or allele frequencies when athletes born outside South Africa were analyzed. To our knowledge this is the first study that has examined the effect of an athlete's ACE genotype on their actual performance during an ultra-endurance race. The I allele of the ACE gene was associated with the endurance performance of the fastest 100 South African-born finishers in these triathlons.