The lingering symptoms of post-COVID-19 condition (long-COVID): a prospective cohort study

BACKGROUND

Longer-term symptoms (long COVID) may be present in seemingly recovered patients for several months and can be debilitating.

AIM

To investigate the prevalence and type of symptoms in those with a prior COVID-19 diagnosis.

METHODS

This prospective, longitudinal observational study commenced in July 2020 investigating the longer-term health impacts of COVID-19. Participants were recruited via public health units and media publicity. Surveys were completed upon enrolment, and at 1, 3, 6 and 12 months. Outcome measures included incidence of activity limitations and symptoms against health and vaccination status, age and gender.

RESULTS

Overall, 339 participants were recruited. At 3 months after COVID-19, 66.8% reported symptoms, and 44.8% were still experiencing symptoms at 12 months. Fatigue was most common at every point (between 53.1% and 33.1%). Pain symptoms increased in relative prevalence over time, whereas respiratory/pulmonary-type symptoms decreased substantially after 3 months. Females and younger people were more likely to experience symptoms in the early stages of long COVID (P < 0.01) and those with more comorbidities in the latter stages (P < 0.001). Vaccination showed a statistically significant protective effect against symptoms (P < 0.01-0.001).

CONCLUSION

Long-term COVID-19 symptoms exist among recovered patients up to 12 months after contracting the virus. Fatigue is a primary contributor, while chronic pain became more problematic after 6 months. Vaccination was a factor in preventing long-term symptoms and aiding faster recovery from symptoms. Further work exploring additional contributors to symptom prevalence would assist in developing appropriate follow-up care.

Fatigue, pain, and the recovery of neuromuscular function after consecutive days of full-body resistance exercise in trained men

PURPOSE

This study measured the self-reported level of fatigue, pain, and neuromuscular function of the knee extensor muscles over a three-day period that included two consecutive days of full-body resistance exercises.

METHODS

10 resistance-trained men performed two consecutive days of full-body resistance exercise. Muscle activation (electromyography and voluntary activation), contractility, and presynaptic inhibition of Ia afferents (homosynaptic and GABA mediated presynaptic inhibition) for the quadriceps were examined from femoral and posterior tibial nerve stimulation.

RESULTS

Fatigue and pain were elevated after Day 1, and were not reduced to pre-exercise levels at the start of Day 2 (p < 0.05). Maximal voluntary torque (- 51.4 Nm, 95% CI = 12.4-90.4 Nm, p = 0.005) and rate of torque development (- 469 Nm.s^-1, 95% CI = 109-829 Nm.s^-1, p = 0.006) were reduced after Day 1, had recovered by Day 2, and did not change after the second training session. The maximal amplitude and rate of rise for the quadriceps twitch were reduced after both training sessions (p < 0.01), with recovery 24 h each session. The maximal amplitude and rate of early muscle activation were reduced after Day 1 (p < 0.01), but no changes were observed for voluntary activation, H-reflex size and shape, or measures of Ia presynaptic inhibition.

CONCLUSION

Resistance exercise in the presence of elevated fatigue and pain from a previous training session does not worsen recovery, or lead to significant alterations in quadriceps neuromuscular function. Reduction in muscle contractility, in the absence of declines in muscle activation, does not lead to decreased voluntary torque.

The effects of d-aspartic acid supplementation in resistance-trained men over a three month training period: A randomised controlled trial

Context

Research on d-aspartic acid (DAA) has demonstrated increases in total testosterone levels in untrained men, however research in resistance-trained men demonstrated no changes, and reductions in testosterone levels. The long-term consequences of DAA in a resistance trained population are currently unknown.

Objective

To evaluate the effectiveness of DAA to alter basal testosterone levels over 3 months of resistance training in resistance-trained men.

Design

Randomised, double-blind, placebo controlled trial in healthy resistance-trained men, aged 18–36, had been performing regular resistance training exercise for at least 3 d.w^-1 for the previous 2 years. Randomised participants were 22 men (d-aspartic acid n = 11; placebo n = 11) (age, 23.8±4.9 y, training age, 3.2±1.5 y).

Intervention

D-aspartic acid (6 g.d^-1, DAA) versus equal-weight, visually-matched placebo (PLA). All participants performed 12 weeks of supervised, periodised resistance training (4 d.w^-1), with a program focusing on all muscle groups.

Measures

Basal hormones, total testosterone (TT), free testosterone (FT), estradiol (E₂), sex-hormone-binding globulin (SHBG) and albumin (ALB); isometric strength; calf muscle cross-sectional area (CSA); calf muscle thickness; quadriceps muscle CSA; quadriceps muscle thickness; evoked V-wave and H-reflexes, were assessed at weeks zero (T1), after six weeks (T2) and after 12 weeks (T3).

Results

No change in basal TT or FT were observed after the intervention. DAA supplementation (n = 10) led to a 16%, 95% CI [-27%, -5%] reduction in E₂ from T1-T3 (p<0.01). The placebo group (n = 9) demonstrated improvements in spinal responsiveness (gastrocnemius) at the level of the alpha motoneuron. Both groups exhibited increases in isometric strength of the plantar flexors by 17%, 95% CI [7%, 28%] (p<0.05) as well as similar increases in hypertrophy in the quadriceps and calf muscles.

Conclusions

The results of this paper indicate that DAA supplementation is ineffective at changing testosterone levels, or positively affecting training outcomes. Reductions in estradiol and the blunting of peripheral excitability appear unrelated to improvements from resistance training.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12617000041358

Three and six grams supplementation of d-aspartic acid in resistance trained men

Background

Although abundant research has investigated the hormonal effects of d-aspartic acid in rat models, to date there is limited research on humans. Previous research has demonstrated increased total testosterone levels in sedentary men and no significant changes in hormonal levels in resistance trained men. It was hypothesised that a higher dosage may be required for experienced lifters, thus this study investigated the effects of two different dosages of d-aspartic acid on basal hormonal levels in resistance trained men and explored responsiveness to d-aspartic acid based on initial testosterone levels.

Methods

Twenty-four males, with a minimum of two years’ experience in resistance training, (age, 24.5 ± 3.2 y; training experience, 3.4 ± 1.4 y; height, 178.5 ± 6.5 cm; weight, 84.7 ± 7.2 kg; bench press 1-RM, 105.3 ± 15.2 kg) were randomised into one of three groups: 6 g.d⁻¹ plain flour (D0); 3 g.d⁻¹ of d-aspartic acid (D3); and 6 g.d⁻¹ of d-aspartic acid (D6). Participants performed a two-week washout period, training four days per week. This continued through the experimental period (14 days), with participants consuming the supplement in the morning. Serum was analysed for levels of testosterone, estradiol, sex hormone binding globulin, albumin and free testosterone was determined by calculation.

Results

D-aspartic acid supplementation revealed no main effect for group in: estradiol; sex-hormone-binding-globulin; and albumin. Total testosterone was significantly reduced in D6 (P = 0.03). Analysis of free testosterone showed that D6 was significantly reduced as compared to D0 (P = 0.005), but not significantly different to D3. Analysis did not reveal any significant differences between D3 and D0. No significant correlation between initial total testosterone levels and responsiveness to d-aspartic acid was observed (r = 0.10, P = 0.70).

Conclusions

The present study demonstrated that a daily dose of six grams of d-aspartic acid decreased levels of total testosterone and free testosterone (D6), without any concurrent change in other hormones measured. Three grams of d-aspartic acid had no significant effect on either testosterone markers. It is currently unknown what effect this reduction in testosterone will have on strength and hypertrophy gains.